Juan C . Levesque, Ph.D. (original) (raw)

Books by Juan C . Levesque, Ph.D.

Papers by Juan C . Levesque, Ph.D.

Fishes, 2017

The management of highly migratory species (HMS) is a complex domestic and international system t... more The management of highly migratory species (HMS) is a complex domestic and international system that was initially established to regulate HMS taken in commercial fisheries in the Atlantic Ocean. For managing HMS taken in recreational fisheries, the authority and the data required is lacking and remains to be stipulated by regulating bodies. In the United States, Florida saltwater anglers target various HMS, but swordfish (Xiphias gladius) is a favorite among anglers. The recreational swordfish fishery off the Southeast Florida coast has experienced resurgence in recent years, with directed tournaments resuming in 2001 after being absent almost 20 years. Today, South Florida supports the largest group of recreational swordfish anglers in the world. Despite the increasing popularity and interest, little data is available describing the recreational swordfish fishery and its socioeconomic aspects in South Florida. This study aimed to compile, describe, and identify the demographics, fishing tactics, costs, and fishery management perceptions of recreational swordfish anglers in South Florida based on nonprobability purposive sampling organized through the Southeast Swordfish Club (SESC). The sample size (n = 38) represented about 16-38% of the SESC members and between 6% and 8% of the recreational anglers that actively targeted swordfish in South Florida during the time of the survey. We acknowledge the sample size was small (n = 38), but believe the study encompassed the most active swordfish anglers given their knowledge, expertise, and connection with the fishery in terms of participants, fishing effort, and fishing techniques. As such, it is highly probable that a large portion of the recreational swordfish angling population was represented by members of the SESC in terms of swordfishing gear, techniques, and socio-economics, which reduced apparent bias in the study. Overall, the annual income of recreational swordfish anglers in 2007 ranged from US$15,000 to 200,000withanaverageincomeof200,000 with an average income of 200,000withanaverageincomeof91,940 (n = 33). Sixty-nine percent of polled anglers indicated they had more than 26 years of recreational fishing experience and 81% had less than 10 years of experience targeting swordfish in South Florida. Thirty-seven percent of surveyed anglers indicated they departed from Port Everglades, Florida. To target swordfish, anglers generally used five rods and set their bait, commonly squid, at 91 m. Anglers also indicated they changed their fishing tactics from day to night, and took about five fishing trips per month. Overall, anglers spent around $14,210 on annual costs associated with swordfishing, which was 16% of their annual income. Many polled anglers also reported they were dissatisfied with the current swordfish management regulations.

PeerJ, 2016

The Ganges River dolphin (Platanista gangetica gangetica) (GRD) is classified as one of the most ... more The Ganges River dolphin (Platanista gangetica gangetica) (GRD) is classified as one of the most endangered of all cetaceans in the world and the second scarcest freshwater cetacean. The population is estimated to be less than 2,000 individuals. In Nepal's Narayani, Sapta Koshi, and Karnali river systems, survival of GRD continues to be threatened by various anthropogenic activities, such as dam construction and interactions with artisanal fisheries. A basic description of the geographic scope, economics, and types of gear used in these fisheries would help managers understand the fishery-dolphin interaction conflict and assist with developing potential solutions. The main goal was to provide new information on the artisanal fishing communities in Nepal. The specific objectives were to identify, compile, and investigate the demographics, economics, fishing characteristics, and perception of fishermen about GRD conservation in the Narayani, Sapta Koshi, and Karnali rivers so conservation managers can develop and implement a potential solution to the GRD-fishery interaction problem in Nepal. Based on 169 interviews, 79% of Nepalese fishermen indicated fishing was their primary form of income. Fishermen reported fishing effort was greater in summer than winter; greatest in the afternoon (14:30 hrs ± 0:27) and during low water level conditions; and gear was set 4.8 ± 0.2 days/week. Fishermen reported using eight different types of monofilament nets (gillnets and cast nets). Sixty percent used gillnets less than 10 m long, and nearly 30% preferred gillnets between 10 and 100 m long; a few used gillnets longer than 100 m. Most fishermen reported they believed education, awareness, and changing occupations were important for GRD conservation, but they indicated that alternative occupational options were currently limited in Nepal. Nepalese fishermen acknowledged that fisheries posed a risk to GRD, but they believed water pollution, and dam/irrigation developments were the greatest threats.

Bycatch of protected species in commercial fishing operations is a primary concern to fishery man... more Bycatch of protected species in commercial fishing operations is a primary concern to fishery managers because it threatens the conservation, protection, and recovery of fragile species, such as the Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus). One potential solution to reduce the risk associated with commercial fishing operations is to design commercial fishing gear that is more selective in terms of interactions between Atlantic sturgeon and commercial fisheries. Given this conservation and management need, the overarching goal was to reduce Atlantic sturgeon fishery interactions and maintain southern flounder (Paralichthys lethostigma) catch in North Carolina. The specific objectives of this study were to design and evaluate the effectiveness of a modified gillnet. Overall, the results proved that lowering the profile and amount of webbing had a beneficial impact at reducing Atlantic sturgeon incidental encounters and bycatch. The modified gillnet reduced bycatch and Atlantic sturgeon encounters by 39.6% and 60.9%, respectively. Our design entangled 51.6% fewer southern flounder, which corresponded to a 48.9% reduction in total weight; the modified gear entangled slightly larger southern flounder than the control gear. Our findings showed the number of Atlantic sturgeon encounters was positively associated with mean water depth, with more Atlantic sturgeon encountered in deeper (5.1–6.3 m) than shallower waters; 75% were encountered at depths between 4.6 and 6.1 m. Most southern flounder (n = 518, 39.7%) were taken at a water depth between 3.76 and 5.0 m. This observation suggests that southern flounder prefer slightly shallower waters than Atlantic sturgeon.

Ladyfish (Elops sp) are a common and economically valuable coastal nearshore species found along ... more Ladyfish (Elops sp) are a common and economically valuable coastal nearshore species found along coastal beaches, bays, and estuaries of the southeastern United States, and subtropical and tropical regions worldwide. Previously, ladyfish were a substantial bycatch in Florida’s commercial fisheries, but changes in regulations significantly reduced commercial landings. Today, ladyfish are still taken in commercial fisheries in Florida, but many are also taken by recreational anglers.
Life-history information and research interest in ladyfish is almost non-existent, especially information on age and growth. Thus, the overarching purpose of this study was to expand our understanding of ladyfish age and growth characteristics.
The specific objectives were to describe, for the first time, age, growth, and recruitment patterns of juvenile ladyfish from the east coast of Florida (USA). In the Indian River Lagoon (IRL), annual monthly length-frequency distributions were confounded because a few small individuals recruited throughout the year; monthly length-frequency data generally demonstrated a cyclical pattern. The smallest were collected in September and the largest inMay. Post-hoc analysis showed
no significant difference in length between August and May, or among the other months. In Volusia County (VC), annual monthly length-frequency distribution demonstrated growth generally occurred from late-winter and spring to summer.
The smallest ladyfish were collected in February and the largest in August. On average, the absolute growth rate in the IRL was 36.3 mm in 60 days or 0.605 mm day−1. Cohort-specific daily growth rates, elevations, and coincidentals were similar
among sampling years. Cohort-specific growth rates ranged from 1.807 in 1993 to 1.811 mm day−1 in 1994. Overall, growth was best (i.e., goodness of fit) described by exponential regression. On average, the absolute growth rate in VC was 28mm in 150 days or 0.1866 mm day−1. Cohort-specific daily growth rates were significantly different among sampling years; however, the elevations and coincidentals were
similar. Cohort-specific growth rates ranged from 1.741 in 1994 to 1.933 mm day−1 in 1993. Mean ladyfish growth was best described by linear regression; however, natural growth was explained better by exponential regression. In the IRL, the
corrected exponential growth equation yielded a size-at-age 1 of 156.0mmSL, which corresponded to an estimated growth rate of 0.4356mmday−1. In VC, the corrected exponential growth equation yielded a size-at-age 1 of 80 mm SL corresponding to an estimated growth rate of 0.2361mmday−1.

The age and growth of juvenile ladyfish (Elops sp) in Tampa Bay, Florida (USA) was examined using... more The age and growth of juvenile ladyfish (Elops sp) in Tampa Bay, Florida (USA) was examined using two cost-effective age and growth methods: length-frequency analysis (LFA) and captive rearing. The progression of monthly ladyfish size significantly increased from the beginning (i.e., when many young and small individuals were collected) to the end (i.e., when fewer older and larger individuals were collected) of the recruitment period. In most years, ladyfish growth (i.e., mean length) in Tampa Bay increased consistently from March to July. Juvenile ladyfish growth calculated by the LFA approach ranged from 0.30 to 1.3 mm day-1, whereas captive reared ladyfish grew between 0.60 and 0.70 mm day-1. Captive rearing data, together with length-frequency data, suggests that juvenile ladyfish reach between 212 and 297 mm SL by age-1. Individuals raised in tanks grew faster than those in the natural
environment during the first 90 days, but slower after 90 days.

Wildlife Biology in Practice, Jun 2013

Marine fish are among the most challenging type of wildlife to examine in the field given their e... more Marine fish are among the most challenging type of wildlife to examine in the field given their expansive range, spatial and temporal distribution, and specific early life-history traits. Different researchers have investigated the catch efficiency of various sampling gears and techniques; however, field-sampling information is mostly unavailable for ladyfish (Elops saurus), an economically valuable species in the southeastern United States. The main purpose of this investigation was to evaluate, for the first time, various sampling gears potentially useful for targeting ladyfish. The specific objectives were to examine and compare differences in capture efficiency and size selectivity of different sampling gears useful for collecting ladyfish in nine Florida water bodies. This investigation found that ladyfish relative abundance, size, and length-frequency distribution varied significantly by sampling gear and geographical location. The findings revealed the most efficient gear for collecting ladyfish smaller than 100 mm SL were seines with an offshore deployment method and the least effective were otter trawls. Overall, seine catch efficiency decreased and gillnet efficiency increased with ladyfish size. These finding indicate it’s essential that researchers use a variety of sampling gears to reduce any potential gear or sampling bias when designing field studies.

Fisheries and Aquaculture Journal, Jun 2013

Commercial and recreational fisheries within the Mid-Atlantic Bight are an important component of... more Commercial and recreational fisheries within the Mid-Atlantic Bight are an important component of the local and national economy. In 2010, commercial fisheries in New Jersey ranked sixth in value ($177,935,588) and eighth in landings (73,406 mt) in the United States. The estimated number of recreational fishing trips in New Jersey ranged from 5.4 million (2009) to 7.4 million (2007) during 2003 through 2010. Because fish communities and the habitats they rely upon can be negatively impacted by anthropogenic activities, descriptive baseline information on the coastal beach fish community beyond the surf zone must be available to marine resource managers so they can make informed decisions. Given this management need to facilitate objective informed marine resource decision-making, the main goal of this investigation was to provide a descriptive profile of the New Jersey coastal fish and invertebrate community. The specific objectives were to assess fish and invertebrate population dynamics by identifying trends (or lack thereof) in spatio-temporal variation in relative abundance and distribution for the most numerically dominant and economically valuable fish and invertebrate species found off the coast of New Jersey. The findings showed that annual relative abundance was stable among species, but there were temporal and spatial differences in overall fish and invertebrate relative abundance among specific species. In addition, results demonstrated there was a seasonal difference in species composition. Overall, butterfish and scup were the most numerically dominant species and relative abundance generally increased from spring to summer. Most fish showed a negative binominal distribution and the highest densities for butterfish and scup occurred at depths between 10 and 20 m.

Fisheries and Aquaculture Journal

Relative abundance and distribution are two of the most important life-history characteristics th... more Relative abundance and distribution are two of the most important life-history characteristics that fishery managers use to make informed decisions, such as identifying nursery grounds or protecting specific habitats. Many researchers have already estimated the relative abundance and distribution of various commercially and recreationally important species (e.g., permit [Trachinotus falcatus], tarpon [Megalops atlanticus], and bonefish [Albula vulpes]) found within and outside of the United States. Unfortunately, comparative information for ladyfish (Elops saurus) is limited and nonexistent for most regions of the world. Given the need to examine the early life-history of ladyfish in more detail, and at a finer scale, the specific objectives of this study were to evaluate the annual relative abundance and distribution (spatial and temporal) of juvenile ladyfish in nine distinct Florida estuaries (USA). Findings showed that juvenile ladyfish recruitment and abundance in Florida waters varied seasonally and annually. Also, the results indicated that juvenile ladyfish recruited into secluded freshwater sites from late-winter to summer depending on the estuary. Annual juvenile ladyfish abundance demonstrated an alternating pattern, and the findings showed that the estimated annual abundance had increased in Tampa Bay and in the Indian River Lagoon during 1987 through 1995. Results also showed that juvenile ladyfish were unevenly distributed throughout Florida estuaries; juvenile ladyfish distribution was skewed towards a limited number of specific locations. It was evident that juvenile ladyfish did not recruit to a wide-variety of habitats; they required specific micro-habitats. In summary, juvenile ladyfish were collected primarily at specific stations located near, or adjacent to, freshwater input or protected bayou areas during late-winter through early summer months.

Fisheries and Aquaculture Journal

Pelagic sharks, an oceanic group of sharks, are an incidental bycatch in many global pelagic long... more Pelagic sharks, an oceanic group of sharks, are an incidental bycatch in many global pelagic longline commercial fisheries, including the U.S commercial longline fishery that operates in the western North Atlantic Ocean. Shortfin mako shark (Isurus oxyrinchus) is one of the only pelagic sharks that have any economic value. Similar to other sharks, the shortfin mako shark is slow-growing, late-to-mature, and has a low fecundity, which makes this species vulnerable to overexploitation. In 2002, the International Union for Conservation of Nature (IUCN) classified the shortfin mako shark as Lower Risk (Near Threatened [NT]) on its annual Red List of Threatened and Endangered Species. Given the current conservation status and the general paucity of data on the status of the shortfin mako shark population, the objectives of this study were to characterize the commercial pelagic longline shortfin mako catch and assess its population in the western North Atlantic Ocean using a simple production model. Commercial data indicated that pelagic longline fishing effort has decreased with time, but most of the fishing effort continued to be in the Gulf of Mexico. Catches of shortfin mako shark have decreased over time, but observer data showed that larger animals were taken in the fishery. Overall, the Schaefer model was generally the least sensitive to varying K values, more sensitive to F values, and the most sensitive to r values.

Marine resource managers designate marine protected areas (MPAs) to conserve, protect, and enhanc... more Marine resource managers designate marine protected areas (MPAs) to conserve, protect, and enhance fragile marine resources. A form of MPAs sometimes used by resource managers in the United States is a national marine sanctuary (NMS), and for all MPAs, managers need to use updated information during sanctuary management plan reviews (MPRs). In 2006, the Flower Garden Banks NMS (FGBNMS) began its first MPR by conducting public hearings and soliciting comments. Some 66% of comments were about the potential impacts fisheries posed to the sanctuary, so a description of commercial fishery activity in the NW Gulf of Mexico can help guide resource managers make sound, informed decisions. Despite limitations on data and knowledge of fishing effort spatially for the FGBNMS, commercial landings vary by Gulf state, area, and fishing gear, with most landings from the Louisiana and Texas coasts taken with trawls and nets. The main species landed from the NW Gulf of Mexico are shrimp, yellowfin tuna, and red snapper. Some conservation measures proposed for the FGBNMS will likely impact some commercial fisheries (hook and line, bottom longline), but not others (otter trawl, pelagic longline).

The demand on our marine resources is increasing at unsustainable rates at the same time that man... more The demand on our marine resources is increasing at unsustainable rates at the same time that many fish stocks are overfished, already collapsed or at risk of extinction. In 2006, recreational anglers landed about 4,809 mt of coastal pelagic species in the Gulf of Mexico, which was above the Maximum Sustainable Yield estimate (4,702 mt). Despite this urgency, marine policy and management is complex, controversial, and time consuming. One tool that resource managers use for managing, protecting, and conserving marine resources is designating Marine Protected Areas (MPAs). Presently, the public is concerned with the impacts of fishing on the status of fish stocks associated with the Flower Garden Banks National Marine Sanctuary (FGBNMS). Recreational fishing is among the most popular marine activities associated with MPAs; however, few studies have evaluated the impact of this activity on the local resources. Given these conservation and social issues, the main goal of this study was to provide a characterization of the recreational fisheries associated with the FGBNMS. Findings showed that recreational landings were dominated by red snapper, vermilion snapper, and gray triggerfish. Cumulative landings and catch rates varied significantly by species, month and location. Overall, the highest fishing effort was in summer, and the highest catch rates were in winter. The greatest catch rates for reef fish and coastal pelagic species were in the southernmost (Laguna Madre) and northernmost (Galveston) origination ports, respectively. Based on monthly catches, there was some evidence that recreational anglers target spawning snapper aggregations. The annual mean weight for gray triggerfish was stable, but the mean weight of both red and vermilion snapper declined between 1986 and 2006.

Understanding a species life history is fundamental for managing and conserving a population. Des... more Understanding a species life history is fundamental for managing and conserving a population. Despite the importance of this type of information, research attention is often directed at species with the highest economic value. This funding approach is problematic for preserving diversity and rarely considers ecological systematic functions; it prevents resource agencies from allocating funds for studying lower-valued species. For example, the ladyfish (Elops saurus) is a valuable commercial and recreational species in Florida, but in comparison to tarpon (Megalops atlanticus) and bonefish (Albula vulpes), ladyfish have received less funding and research attention. To date, comparably little biological information and no recent reviews are available for ladyfish; research interest is almost non-existent. First, a new review of ladyfish information is provided, and second, statistical evidence is presented and discussed that suggests that there is more published information for tarpon and bonefish than ladyfish because their socio-ecological values are greater. This study’s findings confirm that there are significantly more published articles on tarpon than ladyfish, and the number of articles on ladyfish has declined with time.
The number of articles on tarpon and bonefish were positively correlated with time, while the number of articles on ladyfish
was negatively correlated with time. Natural resource management is shifting from a sustainable yield to a sustainable ecosystem perspective. Given this shift in management approach, successful ecosystem management requires substantial biological information on a variety of species within a given system, regardless of their socio-economic status. It is important to understand that although some species have been ranked higher than others, in terms of economic importance, ecosystems are functioning systems that do not discriminate or have any jurisdictional boundaries.

Open Fish Science Journal, Jan 1, 2010

Wildlife and fisheries management are based upon economics: the law of supply and demand controls... more Wildlife and fisheries management are based upon economics: the law of supply and demand controls the direction of commercial fisheries. In the U.S. pelagic longline fishery, one example of a bycatch species that has received
little research attention because of its lower economic value is the escolar (Lepidocybium flavobrunneum). Given its importance as a secondary market species, the main objectives of this paper are to provide information on fishing characteristics, relative abundance, distribution, and size composition of escolar catch in the U.S. pelagic longline fishery operating in the western North Atlantic. The overarching goal is to emphasize the importance of evaluating, managing, and conserving lower-valued species. Findings show that escolar nominal catches significantly vary by geographical area, month, and year. Most escolar are caught in the Gulf of Mexico and off the Florida East Coast (FEC), but mean catch rates are greatest in the FEC and Sargasso Sea. Escolar catch rates are greatest in April, November, and December. Overall, escolar catch rates are stable, which suggests that overfishing is not occurring in this part of the Atlantic.

Natural Resource management is evolving toward ensuring sustainable ecosystems rather than sustai... more Natural Resource management is evolving toward ensuring sustainable ecosystems rather than sustainable yields. Understanding how a species interacts with its environment is fundamental for sound ecosystem management. If we are progressing toward an ecosystem management approach, then we must first understand how a species interacts with its environment and how the environment affects a species population dynamics. Ladyfish (Elops saurus) are a valuable commercial and recreational species; however, limited information is available describing the importance of their habitat. To date, only a few studies have noted the environmental conditions during ladyfish field-collections, and only one study has investigated ladyfish nursery habitats in any detail. Given the economic importance of ladyfish in Florida (USA), the objective of this investigation was to define, for the first time, juvenile ladyfish relative abundance in association to environmental conditions and habitat use at multiple Florida estuaries. In addition, this investigation re-examined some of the scientific findings and conclusions of previous ladyfish studies; incorporated additional data sets; and evaluated available ladyfish data at a finer scale of phenomena. Overall, juvenile ladyfish were collected in waters with wide-ranging environmental conditions having a sandy bottom, but preferred specific locations with particular dissolved oxygen, pH, water temperature, and salinity levels according to their size.

Marine Policy, Jan 1, 2009

A vital component of coastal management and marine policy is the conservation and management of d... more A vital component of coastal management and marine policy is the conservation and management of diverse marine resources. In the southeastern U.S., commercial fishermen target black sea bass (Centropristis striata) with pots from North Carolina to Cape Canaveral, Florida. During the fall through spring fishing season, western North Atlantic right whale (Eubalaena glacialis) distribution overlaps the black sea bass commercial pot fishery. Fishermen interviews revealed that the number of pots set ranged from 3 to 240 and the number of pots set per trawl ranged from 1 to 18. Generally, the amount of gear increased from south to north.

Marine Policy, Jan 1, 2009

Florida Scientist, Jan 1, 2007

Marine Policy, Jan 1, 2008

To properly manage world fisheries, especially highly migratory species, there are numerous treat... more To properly manage world fisheries, especially highly migratory species, there are numerous treaties that have been implemented by specialized international fishery commissions. One of the oldest organizations is the International Commission for the Conservation of Atlantic Tunas (ICCAT). The main focus of this review was to summarize the history, roles and responsibilities of ICCAT, and to evaluate ICCAT’s management of sharks in general and specifically for shortfin mako (Isurus oxyrinchus) shark. This review found that the Convention was established 40 years ago, but it was not until 2004 that the commission conducted its first population assessment on pelagic sharks.

Fishes, 2017

The management of highly migratory species (HMS) is a complex domestic and international system t... more The management of highly migratory species (HMS) is a complex domestic and international system that was initially established to regulate HMS taken in commercial fisheries in the Atlantic Ocean. For managing HMS taken in recreational fisheries, the authority and the data required is lacking and remains to be stipulated by regulating bodies. In the United States, Florida saltwater anglers target various HMS, but swordfish (Xiphias gladius) is a favorite among anglers. The recreational swordfish fishery off the Southeast Florida coast has experienced resurgence in recent years, with directed tournaments resuming in 2001 after being absent almost 20 years. Today, South Florida supports the largest group of recreational swordfish anglers in the world. Despite the increasing popularity and interest, little data is available describing the recreational swordfish fishery and its socioeconomic aspects in South Florida. This study aimed to compile, describe, and identify the demographics, fishing tactics, costs, and fishery management perceptions of recreational swordfish anglers in South Florida based on nonprobability purposive sampling organized through the Southeast Swordfish Club (SESC). The sample size (n = 38) represented about 16-38% of the SESC members and between 6% and 8% of the recreational anglers that actively targeted swordfish in South Florida during the time of the survey. We acknowledge the sample size was small (n = 38), but believe the study encompassed the most active swordfish anglers given their knowledge, expertise, and connection with the fishery in terms of participants, fishing effort, and fishing techniques. As such, it is highly probable that a large portion of the recreational swordfish angling population was represented by members of the SESC in terms of swordfishing gear, techniques, and socio-economics, which reduced apparent bias in the study. Overall, the annual income of recreational swordfish anglers in 2007 ranged from US$15,000 to 200,000withanaverageincomeof200,000 with an average income of 200,000withanaverageincomeof91,940 (n = 33). Sixty-nine percent of polled anglers indicated they had more than 26 years of recreational fishing experience and 81% had less than 10 years of experience targeting swordfish in South Florida. Thirty-seven percent of surveyed anglers indicated they departed from Port Everglades, Florida. To target swordfish, anglers generally used five rods and set their bait, commonly squid, at 91 m. Anglers also indicated they changed their fishing tactics from day to night, and took about five fishing trips per month. Overall, anglers spent around $14,210 on annual costs associated with swordfishing, which was 16% of their annual income. Many polled anglers also reported they were dissatisfied with the current swordfish management regulations.

PeerJ, 2016

The Ganges River dolphin (Platanista gangetica gangetica) (GRD) is classified as one of the most ... more The Ganges River dolphin (Platanista gangetica gangetica) (GRD) is classified as one of the most endangered of all cetaceans in the world and the second scarcest freshwater cetacean. The population is estimated to be less than 2,000 individuals. In Nepal's Narayani, Sapta Koshi, and Karnali river systems, survival of GRD continues to be threatened by various anthropogenic activities, such as dam construction and interactions with artisanal fisheries. A basic description of the geographic scope, economics, and types of gear used in these fisheries would help managers understand the fishery-dolphin interaction conflict and assist with developing potential solutions. The main goal was to provide new information on the artisanal fishing communities in Nepal. The specific objectives were to identify, compile, and investigate the demographics, economics, fishing characteristics, and perception of fishermen about GRD conservation in the Narayani, Sapta Koshi, and Karnali rivers so conservation managers can develop and implement a potential solution to the GRD-fishery interaction problem in Nepal. Based on 169 interviews, 79% of Nepalese fishermen indicated fishing was their primary form of income. Fishermen reported fishing effort was greater in summer than winter; greatest in the afternoon (14:30 hrs ± 0:27) and during low water level conditions; and gear was set 4.8 ± 0.2 days/week. Fishermen reported using eight different types of monofilament nets (gillnets and cast nets). Sixty percent used gillnets less than 10 m long, and nearly 30% preferred gillnets between 10 and 100 m long; a few used gillnets longer than 100 m. Most fishermen reported they believed education, awareness, and changing occupations were important for GRD conservation, but they indicated that alternative occupational options were currently limited in Nepal. Nepalese fishermen acknowledged that fisheries posed a risk to GRD, but they believed water pollution, and dam/irrigation developments were the greatest threats.

Bycatch of protected species in commercial fishing operations is a primary concern to fishery man... more Bycatch of protected species in commercial fishing operations is a primary concern to fishery managers because it threatens the conservation, protection, and recovery of fragile species, such as the Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus). One potential solution to reduce the risk associated with commercial fishing operations is to design commercial fishing gear that is more selective in terms of interactions between Atlantic sturgeon and commercial fisheries. Given this conservation and management need, the overarching goal was to reduce Atlantic sturgeon fishery interactions and maintain southern flounder (Paralichthys lethostigma) catch in North Carolina. The specific objectives of this study were to design and evaluate the effectiveness of a modified gillnet. Overall, the results proved that lowering the profile and amount of webbing had a beneficial impact at reducing Atlantic sturgeon incidental encounters and bycatch. The modified gillnet reduced bycatch and Atlantic sturgeon encounters by 39.6% and 60.9%, respectively. Our design entangled 51.6% fewer southern flounder, which corresponded to a 48.9% reduction in total weight; the modified gear entangled slightly larger southern flounder than the control gear. Our findings showed the number of Atlantic sturgeon encounters was positively associated with mean water depth, with more Atlantic sturgeon encountered in deeper (5.1–6.3 m) than shallower waters; 75% were encountered at depths between 4.6 and 6.1 m. Most southern flounder (n = 518, 39.7%) were taken at a water depth between 3.76 and 5.0 m. This observation suggests that southern flounder prefer slightly shallower waters than Atlantic sturgeon.

Ladyfish (Elops sp) are a common and economically valuable coastal nearshore species found along ... more Ladyfish (Elops sp) are a common and economically valuable coastal nearshore species found along coastal beaches, bays, and estuaries of the southeastern United States, and subtropical and tropical regions worldwide. Previously, ladyfish were a substantial bycatch in Florida’s commercial fisheries, but changes in regulations significantly reduced commercial landings. Today, ladyfish are still taken in commercial fisheries in Florida, but many are also taken by recreational anglers.
Life-history information and research interest in ladyfish is almost non-existent, especially information on age and growth. Thus, the overarching purpose of this study was to expand our understanding of ladyfish age and growth characteristics.
The specific objectives were to describe, for the first time, age, growth, and recruitment patterns of juvenile ladyfish from the east coast of Florida (USA). In the Indian River Lagoon (IRL), annual monthly length-frequency distributions were confounded because a few small individuals recruited throughout the year; monthly length-frequency data generally demonstrated a cyclical pattern. The smallest were collected in September and the largest inMay. Post-hoc analysis showed
no significant difference in length between August and May, or among the other months. In Volusia County (VC), annual monthly length-frequency distribution demonstrated growth generally occurred from late-winter and spring to summer.
The smallest ladyfish were collected in February and the largest in August. On average, the absolute growth rate in the IRL was 36.3 mm in 60 days or 0.605 mm day−1. Cohort-specific daily growth rates, elevations, and coincidentals were similar
among sampling years. Cohort-specific growth rates ranged from 1.807 in 1993 to 1.811 mm day−1 in 1994. Overall, growth was best (i.e., goodness of fit) described by exponential regression. On average, the absolute growth rate in VC was 28mm in 150 days or 0.1866 mm day−1. Cohort-specific daily growth rates were significantly different among sampling years; however, the elevations and coincidentals were
similar. Cohort-specific growth rates ranged from 1.741 in 1994 to 1.933 mm day−1 in 1993. Mean ladyfish growth was best described by linear regression; however, natural growth was explained better by exponential regression. In the IRL, the
corrected exponential growth equation yielded a size-at-age 1 of 156.0mmSL, which corresponded to an estimated growth rate of 0.4356mmday−1. In VC, the corrected exponential growth equation yielded a size-at-age 1 of 80 mm SL corresponding to an estimated growth rate of 0.2361mmday−1.

The age and growth of juvenile ladyfish (Elops sp) in Tampa Bay, Florida (USA) was examined using... more The age and growth of juvenile ladyfish (Elops sp) in Tampa Bay, Florida (USA) was examined using two cost-effective age and growth methods: length-frequency analysis (LFA) and captive rearing. The progression of monthly ladyfish size significantly increased from the beginning (i.e., when many young and small individuals were collected) to the end (i.e., when fewer older and larger individuals were collected) of the recruitment period. In most years, ladyfish growth (i.e., mean length) in Tampa Bay increased consistently from March to July. Juvenile ladyfish growth calculated by the LFA approach ranged from 0.30 to 1.3 mm day-1, whereas captive reared ladyfish grew between 0.60 and 0.70 mm day-1. Captive rearing data, together with length-frequency data, suggests that juvenile ladyfish reach between 212 and 297 mm SL by age-1. Individuals raised in tanks grew faster than those in the natural
environment during the first 90 days, but slower after 90 days.

Wildlife Biology in Practice, Jun 2013

Marine fish are among the most challenging type of wildlife to examine in the field given their e... more Marine fish are among the most challenging type of wildlife to examine in the field given their expansive range, spatial and temporal distribution, and specific early life-history traits. Different researchers have investigated the catch efficiency of various sampling gears and techniques; however, field-sampling information is mostly unavailable for ladyfish (Elops saurus), an economically valuable species in the southeastern United States. The main purpose of this investigation was to evaluate, for the first time, various sampling gears potentially useful for targeting ladyfish. The specific objectives were to examine and compare differences in capture efficiency and size selectivity of different sampling gears useful for collecting ladyfish in nine Florida water bodies. This investigation found that ladyfish relative abundance, size, and length-frequency distribution varied significantly by sampling gear and geographical location. The findings revealed the most efficient gear for collecting ladyfish smaller than 100 mm SL were seines with an offshore deployment method and the least effective were otter trawls. Overall, seine catch efficiency decreased and gillnet efficiency increased with ladyfish size. These finding indicate it’s essential that researchers use a variety of sampling gears to reduce any potential gear or sampling bias when designing field studies.

Fisheries and Aquaculture Journal, Jun 2013

Commercial and recreational fisheries within the Mid-Atlantic Bight are an important component of... more Commercial and recreational fisheries within the Mid-Atlantic Bight are an important component of the local and national economy. In 2010, commercial fisheries in New Jersey ranked sixth in value ($177,935,588) and eighth in landings (73,406 mt) in the United States. The estimated number of recreational fishing trips in New Jersey ranged from 5.4 million (2009) to 7.4 million (2007) during 2003 through 2010. Because fish communities and the habitats they rely upon can be negatively impacted by anthropogenic activities, descriptive baseline information on the coastal beach fish community beyond the surf zone must be available to marine resource managers so they can make informed decisions. Given this management need to facilitate objective informed marine resource decision-making, the main goal of this investigation was to provide a descriptive profile of the New Jersey coastal fish and invertebrate community. The specific objectives were to assess fish and invertebrate population dynamics by identifying trends (or lack thereof) in spatio-temporal variation in relative abundance and distribution for the most numerically dominant and economically valuable fish and invertebrate species found off the coast of New Jersey. The findings showed that annual relative abundance was stable among species, but there were temporal and spatial differences in overall fish and invertebrate relative abundance among specific species. In addition, results demonstrated there was a seasonal difference in species composition. Overall, butterfish and scup were the most numerically dominant species and relative abundance generally increased from spring to summer. Most fish showed a negative binominal distribution and the highest densities for butterfish and scup occurred at depths between 10 and 20 m.

Fisheries and Aquaculture Journal

Relative abundance and distribution are two of the most important life-history characteristics th... more Relative abundance and distribution are two of the most important life-history characteristics that fishery managers use to make informed decisions, such as identifying nursery grounds or protecting specific habitats. Many researchers have already estimated the relative abundance and distribution of various commercially and recreationally important species (e.g., permit [Trachinotus falcatus], tarpon [Megalops atlanticus], and bonefish [Albula vulpes]) found within and outside of the United States. Unfortunately, comparative information for ladyfish (Elops saurus) is limited and nonexistent for most regions of the world. Given the need to examine the early life-history of ladyfish in more detail, and at a finer scale, the specific objectives of this study were to evaluate the annual relative abundance and distribution (spatial and temporal) of juvenile ladyfish in nine distinct Florida estuaries (USA). Findings showed that juvenile ladyfish recruitment and abundance in Florida waters varied seasonally and annually. Also, the results indicated that juvenile ladyfish recruited into secluded freshwater sites from late-winter to summer depending on the estuary. Annual juvenile ladyfish abundance demonstrated an alternating pattern, and the findings showed that the estimated annual abundance had increased in Tampa Bay and in the Indian River Lagoon during 1987 through 1995. Results also showed that juvenile ladyfish were unevenly distributed throughout Florida estuaries; juvenile ladyfish distribution was skewed towards a limited number of specific locations. It was evident that juvenile ladyfish did not recruit to a wide-variety of habitats; they required specific micro-habitats. In summary, juvenile ladyfish were collected primarily at specific stations located near, or adjacent to, freshwater input or protected bayou areas during late-winter through early summer months.

Fisheries and Aquaculture Journal

Pelagic sharks, an oceanic group of sharks, are an incidental bycatch in many global pelagic long... more Pelagic sharks, an oceanic group of sharks, are an incidental bycatch in many global pelagic longline commercial fisheries, including the U.S commercial longline fishery that operates in the western North Atlantic Ocean. Shortfin mako shark (Isurus oxyrinchus) is one of the only pelagic sharks that have any economic value. Similar to other sharks, the shortfin mako shark is slow-growing, late-to-mature, and has a low fecundity, which makes this species vulnerable to overexploitation. In 2002, the International Union for Conservation of Nature (IUCN) classified the shortfin mako shark as Lower Risk (Near Threatened [NT]) on its annual Red List of Threatened and Endangered Species. Given the current conservation status and the general paucity of data on the status of the shortfin mako shark population, the objectives of this study were to characterize the commercial pelagic longline shortfin mako catch and assess its population in the western North Atlantic Ocean using a simple production model. Commercial data indicated that pelagic longline fishing effort has decreased with time, but most of the fishing effort continued to be in the Gulf of Mexico. Catches of shortfin mako shark have decreased over time, but observer data showed that larger animals were taken in the fishery. Overall, the Schaefer model was generally the least sensitive to varying K values, more sensitive to F values, and the most sensitive to r values.

Marine resource managers designate marine protected areas (MPAs) to conserve, protect, and enhanc... more Marine resource managers designate marine protected areas (MPAs) to conserve, protect, and enhance fragile marine resources. A form of MPAs sometimes used by resource managers in the United States is a national marine sanctuary (NMS), and for all MPAs, managers need to use updated information during sanctuary management plan reviews (MPRs). In 2006, the Flower Garden Banks NMS (FGBNMS) began its first MPR by conducting public hearings and soliciting comments. Some 66% of comments were about the potential impacts fisheries posed to the sanctuary, so a description of commercial fishery activity in the NW Gulf of Mexico can help guide resource managers make sound, informed decisions. Despite limitations on data and knowledge of fishing effort spatially for the FGBNMS, commercial landings vary by Gulf state, area, and fishing gear, with most landings from the Louisiana and Texas coasts taken with trawls and nets. The main species landed from the NW Gulf of Mexico are shrimp, yellowfin tuna, and red snapper. Some conservation measures proposed for the FGBNMS will likely impact some commercial fisheries (hook and line, bottom longline), but not others (otter trawl, pelagic longline).

The demand on our marine resources is increasing at unsustainable rates at the same time that man... more The demand on our marine resources is increasing at unsustainable rates at the same time that many fish stocks are overfished, already collapsed or at risk of extinction. In 2006, recreational anglers landed about 4,809 mt of coastal pelagic species in the Gulf of Mexico, which was above the Maximum Sustainable Yield estimate (4,702 mt). Despite this urgency, marine policy and management is complex, controversial, and time consuming. One tool that resource managers use for managing, protecting, and conserving marine resources is designating Marine Protected Areas (MPAs). Presently, the public is concerned with the impacts of fishing on the status of fish stocks associated with the Flower Garden Banks National Marine Sanctuary (FGBNMS). Recreational fishing is among the most popular marine activities associated with MPAs; however, few studies have evaluated the impact of this activity on the local resources. Given these conservation and social issues, the main goal of this study was to provide a characterization of the recreational fisheries associated with the FGBNMS. Findings showed that recreational landings were dominated by red snapper, vermilion snapper, and gray triggerfish. Cumulative landings and catch rates varied significantly by species, month and location. Overall, the highest fishing effort was in summer, and the highest catch rates were in winter. The greatest catch rates for reef fish and coastal pelagic species were in the southernmost (Laguna Madre) and northernmost (Galveston) origination ports, respectively. Based on monthly catches, there was some evidence that recreational anglers target spawning snapper aggregations. The annual mean weight for gray triggerfish was stable, but the mean weight of both red and vermilion snapper declined between 1986 and 2006.

Understanding a species life history is fundamental for managing and conserving a population. Des... more Understanding a species life history is fundamental for managing and conserving a population. Despite the importance of this type of information, research attention is often directed at species with the highest economic value. This funding approach is problematic for preserving diversity and rarely considers ecological systematic functions; it prevents resource agencies from allocating funds for studying lower-valued species. For example, the ladyfish (Elops saurus) is a valuable commercial and recreational species in Florida, but in comparison to tarpon (Megalops atlanticus) and bonefish (Albula vulpes), ladyfish have received less funding and research attention. To date, comparably little biological information and no recent reviews are available for ladyfish; research interest is almost non-existent. First, a new review of ladyfish information is provided, and second, statistical evidence is presented and discussed that suggests that there is more published information for tarpon and bonefish than ladyfish because their socio-ecological values are greater. This study’s findings confirm that there are significantly more published articles on tarpon than ladyfish, and the number of articles on ladyfish has declined with time.
The number of articles on tarpon and bonefish were positively correlated with time, while the number of articles on ladyfish
was negatively correlated with time. Natural resource management is shifting from a sustainable yield to a sustainable ecosystem perspective. Given this shift in management approach, successful ecosystem management requires substantial biological information on a variety of species within a given system, regardless of their socio-economic status. It is important to understand that although some species have been ranked higher than others, in terms of economic importance, ecosystems are functioning systems that do not discriminate or have any jurisdictional boundaries.

Open Fish Science Journal, Jan 1, 2010

Wildlife and fisheries management are based upon economics: the law of supply and demand controls... more Wildlife and fisheries management are based upon economics: the law of supply and demand controls the direction of commercial fisheries. In the U.S. pelagic longline fishery, one example of a bycatch species that has received
little research attention because of its lower economic value is the escolar (Lepidocybium flavobrunneum). Given its importance as a secondary market species, the main objectives of this paper are to provide information on fishing characteristics, relative abundance, distribution, and size composition of escolar catch in the U.S. pelagic longline fishery operating in the western North Atlantic. The overarching goal is to emphasize the importance of evaluating, managing, and conserving lower-valued species. Findings show that escolar nominal catches significantly vary by geographical area, month, and year. Most escolar are caught in the Gulf of Mexico and off the Florida East Coast (FEC), but mean catch rates are greatest in the FEC and Sargasso Sea. Escolar catch rates are greatest in April, November, and December. Overall, escolar catch rates are stable, which suggests that overfishing is not occurring in this part of the Atlantic.

Natural Resource management is evolving toward ensuring sustainable ecosystems rather than sustai... more Natural Resource management is evolving toward ensuring sustainable ecosystems rather than sustainable yields. Understanding how a species interacts with its environment is fundamental for sound ecosystem management. If we are progressing toward an ecosystem management approach, then we must first understand how a species interacts with its environment and how the environment affects a species population dynamics. Ladyfish (Elops saurus) are a valuable commercial and recreational species; however, limited information is available describing the importance of their habitat. To date, only a few studies have noted the environmental conditions during ladyfish field-collections, and only one study has investigated ladyfish nursery habitats in any detail. Given the economic importance of ladyfish in Florida (USA), the objective of this investigation was to define, for the first time, juvenile ladyfish relative abundance in association to environmental conditions and habitat use at multiple Florida estuaries. In addition, this investigation re-examined some of the scientific findings and conclusions of previous ladyfish studies; incorporated additional data sets; and evaluated available ladyfish data at a finer scale of phenomena. Overall, juvenile ladyfish were collected in waters with wide-ranging environmental conditions having a sandy bottom, but preferred specific locations with particular dissolved oxygen, pH, water temperature, and salinity levels according to their size.

Marine Policy, Jan 1, 2009

A vital component of coastal management and marine policy is the conservation and management of d... more A vital component of coastal management and marine policy is the conservation and management of diverse marine resources. In the southeastern U.S., commercial fishermen target black sea bass (Centropristis striata) with pots from North Carolina to Cape Canaveral, Florida. During the fall through spring fishing season, western North Atlantic right whale (Eubalaena glacialis) distribution overlaps the black sea bass commercial pot fishery. Fishermen interviews revealed that the number of pots set ranged from 3 to 240 and the number of pots set per trawl ranged from 1 to 18. Generally, the amount of gear increased from south to north.

Marine Policy, Jan 1, 2009

Florida Scientist, Jan 1, 2007

Marine Policy, Jan 1, 2008

To properly manage world fisheries, especially highly migratory species, there are numerous treat... more To properly manage world fisheries, especially highly migratory species, there are numerous treaties that have been implemented by specialized international fishery commissions. One of the oldest organizations is the International Commission for the Conservation of Atlantic Tunas (ICCAT). The main focus of this review was to summarize the history, roles and responsibilities of ICCAT, and to evaluate ICCAT’s management of sharks in general and specifically for shortfin mako (Isurus oxyrinchus) shark. This review found that the Convention was established 40 years ago, but it was not until 2004 that the commission conducted its first population assessment on pelagic sharks.