Dean Grubbs | Florida State University (original) (raw)
Papers by Dean Grubbs
Copeia, 2020
Given the conservation status and ecological, cultural, and commercial importance of chondrichthy... more Given the conservation status and ecological, cultural, and commercial importance of chondrichthyan fishes, it is valuable to evaluate the extent to which research attention is spread across taxa and geographic locations and to assess the degree to which scientific research is appropriately addressing the challenges they face. Here we review trends in research effort over three decades (1985-2016) through content analysis of every abstract (n ¼ 2,701) presented at the annual conference of the American Elasmobranch Society (AES), the oldest and largest professional society focused on the scientific study and management of these fishes. The most common research areas of AES abstracts were reproductive biology, movement/telemetry, age and growth, population genetics, and diet/feeding ecology, with different areas of focus for different study species or families. The most commonly studied species were large and charismatic (e.g., White Shark, Carcharodon carcharias), easily accessible to long-term established field research programs (e.g., Lemon Shark, Negaprion brevirostris, and Sandbar Shark, Carcharhinus plumbeus), or easily kept in aquaria for lab-based research (e.g., Bonnethead Shark, Sphyrna tiburo). Nearly 90% of all described chondrichthyan species have never been mentioned in an AES abstract, including some of the most threatened species in the Americas. The proportion of female* first authors has increased over time, though many current female* Society members are graduate students. Nearly half of all research presented at AES occurred in the waters of the United States rather than in the waters of developing nations where there are more threatened species and few resources for research or management. Presentations based on research areas such as paleontology and aquarium-based research have declined in frequency over time, and identified research priorities such as social science and interdisciplinary research are poorly represented. Possible research gaps and future research priorities for the study of chondrichthyan fishes are also discussed.
Scientific Reports, 2016
When identifying potential trophic cascades, it is important to clearly establish the trophic lin... more When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the "Save the Bay, Eat a Ray" fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions.
Molecular phylogenetics and evolution, Nov 27, 2016
Here we consider the role of depth as a driver of evolution in a genus of deep-sea fishes. We pro... more Here we consider the role of depth as a driver of evolution in a genus of deep-sea fishes. We provide a phylogeny for the genus Coryphaenoides (Gadiformes: Macrouridae) that represents the breadth of habitat use and distributions for these species. In our consensus phylogeny species found at abyssal depths (>4000m) form a well-supported lineage, which interestingly also includes two non-abyssal species, C. striaturus and C. murrayi, diverging from the basal node of that lineage. Biogeographic analyses suggest the genus may have originated in the Southern and Pacific Oceans where contemporary species diversity is highest. The abyssal lineage seems to have arisen secondarily and likely originated in the Southern/Pacific Oceans but diversification of this lineage occurred in the Northern Atlantic Ocean. All abyssal species are found in the North Atlantic with the exception of C. yaquinae in the North Pacific and C. filicauda in the Southern Ocean. Abyssal species tend to have broad ...
PloS one, 2014
White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they... more White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A recent tag-recapture study used photographic identifications of white sharks at two aggregation sites to estimate abundance in "central California" at 219 mature and sub-adult individuals. They concluded this represented approximately one-half of the total abundance of mature and sub-adult sharks in the entire eastern North Pacific Ocean (ENP). This low estimate generated great concern within the conservation community, prompting petitions for governmental endangered species designations. We critically examine that study and find violations of model assumptions that, when considered in total, lead to population underestimates. We also use a Bayesian mixture model to demonstrate that the inclusion of transient sharks, characteristic of white sha...
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013
1. Research on rare and threatened species is often limited by access to sufficient individuals t... more 1. Research on rare and threatened species is often limited by access to sufficient individuals to acquire information needed to design appropriate conservation measures. 2. Using a combination of data from pop-up archival transmitting (PAT) tags across multiple institutional programmes, movements and habitat use of endangered smalltooth sawfish, Pristis pectinata were determined for animals from southern Florida and the Bahamas. 3. All P. pectinata (n = 12) generally remained in coastal waters within the region where they were initially tagged, travelling an average of 80.2 km from deployment to pop-up location. The shortest distance moved was 4.6 km and the greatest 279.1 km, averaging 1.4 km day-1. Seasonal movement rates for females were significantly different with the greatest movements in autumn and winter. 4. Pristis pectinata spent the majority of their time at shallow depths (96% of their time at depths <10 m) and warm water temperatures (22-28°C). 5. Given sawfish show a degree of site fidelity punctuated by limited migratory movements emphasizes the need for conservation and management of existing coastal habitats throughout the species' range. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Introduction Most tropical tunas captured by commercial and recreational fishers worldwide are “a... more Introduction Most tropical tunas captured by commercial and recreational fishers worldwide are “associated.” Sometimes this association is with natural structures such as seamounts or reefs or drifting logs, but increasingly these associations are with man-made fish aggregating devices—FADS. In fact, some researchers estimate that over 50%, by weight, of total tuna catch in the Indian and Pacific Oceans is now taken near FADs. FAD deployment has increased steadily over the last 25 years, and has become rampant over the last decade. Until recently, there has been very little consideration of the ecological impact of the practice. Understanding the amount of time that tuna spend in association with FADs and the trophic dynamics of FAD-associated tuna are critical to evaluating the impact of FADs on tuna distribution, their vulnerability to fishing gear, and the impact of FADs on their overall well being. To address these issues, we have embarked on a comprehensive investigation of the...
Copeia, 2020
Given the conservation status and ecological, cultural, and commercial importance of chondrichthy... more Given the conservation status and ecological, cultural, and commercial importance of chondrichthyan fishes, it is valuable to evaluate the extent to which research attention is spread across taxa and geographic locations and to assess the degree to which scientific research is appropriately addressing the challenges they face. Here we review trends in research effort over three decades (1985-2016) through content analysis of every abstract (n ¼ 2,701) presented at the annual conference of the American Elasmobranch Society (AES), the oldest and largest professional society focused on the scientific study and management of these fishes. The most common research areas of AES abstracts were reproductive biology, movement/telemetry, age and growth, population genetics, and diet/feeding ecology, with different areas of focus for different study species or families. The most commonly studied species were large and charismatic (e.g., White Shark, Carcharodon carcharias), easily accessible to long-term established field research programs (e.g., Lemon Shark, Negaprion brevirostris, and Sandbar Shark, Carcharhinus plumbeus), or easily kept in aquaria for lab-based research (e.g., Bonnethead Shark, Sphyrna tiburo). Nearly 90% of all described chondrichthyan species have never been mentioned in an AES abstract, including some of the most threatened species in the Americas. The proportion of female* first authors has increased over time, though many current female* Society members are graduate students. Nearly half of all research presented at AES occurred in the waters of the United States rather than in the waters of developing nations where there are more threatened species and few resources for research or management. Presentations based on research areas such as paleontology and aquarium-based research have declined in frequency over time, and identified research priorities such as social science and interdisciplinary research are poorly represented. Possible research gaps and future research priorities for the study of chondrichthyan fishes are also discussed.
Scientific Reports, 2016
When identifying potential trophic cascades, it is important to clearly establish the trophic lin... more When identifying potential trophic cascades, it is important to clearly establish the trophic linkages between predators and prey with respect to temporal abundance, demographics, distribution, and diet. In the northwest Atlantic Ocean, the depletion of large coastal sharks was thought to trigger a trophic cascade whereby predation release resulted in increased cownose ray abundance, which then caused increased predation on and subsequent collapse of commercial bivalve stocks. These claims were used to justify the development of a predator-control fishery for cownose rays, the "Save the Bay, Eat a Ray" fishery, to reduce predation on commercial bivalves. A reexamination of data suggests declines in large coastal sharks did not coincide with purported rapid increases in cownose ray abundance. Likewise, the increase in cownose ray abundance did not coincide with declines in commercial bivalves. The lack of temporal correlations coupled with published diet data suggest the purported trophic cascade is lacking the empirical linkages required of a trophic cascade. Furthermore, the life history parameters of cownose rays suggest they have low reproductive potential and their populations are incapable of rapid increases. Hypothesized trophic cascades should be closely scrutinized as spurious conclusions may negatively influence conservation and management decisions.
Molecular phylogenetics and evolution, Nov 27, 2016
Here we consider the role of depth as a driver of evolution in a genus of deep-sea fishes. We pro... more Here we consider the role of depth as a driver of evolution in a genus of deep-sea fishes. We provide a phylogeny for the genus Coryphaenoides (Gadiformes: Macrouridae) that represents the breadth of habitat use and distributions for these species. In our consensus phylogeny species found at abyssal depths (>4000m) form a well-supported lineage, which interestingly also includes two non-abyssal species, C. striaturus and C. murrayi, diverging from the basal node of that lineage. Biogeographic analyses suggest the genus may have originated in the Southern and Pacific Oceans where contemporary species diversity is highest. The abyssal lineage seems to have arisen secondarily and likely originated in the Southern/Pacific Oceans but diversification of this lineage occurred in the Northern Atlantic Ocean. All abyssal species are found in the North Atlantic with the exception of C. yaquinae in the North Pacific and C. filicauda in the Southern Ocean. Abyssal species tend to have broad ...
PloS one, 2014
White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they... more White sharks are highly migratory and segregate by sex, age and size. Unlike marine mammals, they neither surface to breathe nor frequent haul-out sites, hindering generation of abundance data required to estimate population size. A recent tag-recapture study used photographic identifications of white sharks at two aggregation sites to estimate abundance in "central California" at 219 mature and sub-adult individuals. They concluded this represented approximately one-half of the total abundance of mature and sub-adult sharks in the entire eastern North Pacific Ocean (ENP). This low estimate generated great concern within the conservation community, prompting petitions for governmental endangered species designations. We critically examine that study and find violations of model assumptions that, when considered in total, lead to population underestimates. We also use a Bayesian mixture model to demonstrate that the inclusion of transient sharks, characteristic of white sha...
Aquatic Conservation: Marine and Freshwater Ecosystems, 2013
1. Research on rare and threatened species is often limited by access to sufficient individuals t... more 1. Research on rare and threatened species is often limited by access to sufficient individuals to acquire information needed to design appropriate conservation measures. 2. Using a combination of data from pop-up archival transmitting (PAT) tags across multiple institutional programmes, movements and habitat use of endangered smalltooth sawfish, Pristis pectinata were determined for animals from southern Florida and the Bahamas. 3. All P. pectinata (n = 12) generally remained in coastal waters within the region where they were initially tagged, travelling an average of 80.2 km from deployment to pop-up location. The shortest distance moved was 4.6 km and the greatest 279.1 km, averaging 1.4 km day-1. Seasonal movement rates for females were significantly different with the greatest movements in autumn and winter. 4. Pristis pectinata spent the majority of their time at shallow depths (96% of their time at depths <10 m) and warm water temperatures (22-28°C). 5. Given sawfish show a degree of site fidelity punctuated by limited migratory movements emphasizes the need for conservation and management of existing coastal habitats throughout the species' range. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Introduction Most tropical tunas captured by commercial and recreational fishers worldwide are “a... more Introduction Most tropical tunas captured by commercial and recreational fishers worldwide are “associated.” Sometimes this association is with natural structures such as seamounts or reefs or drifting logs, but increasingly these associations are with man-made fish aggregating devices—FADS. In fact, some researchers estimate that over 50%, by weight, of total tuna catch in the Indian and Pacific Oceans is now taken near FADs. FAD deployment has increased steadily over the last 25 years, and has become rampant over the last decade. Until recently, there has been very little consideration of the ecological impact of the practice. Understanding the amount of time that tuna spend in association with FADs and the trophic dynamics of FAD-associated tuna are critical to evaluating the impact of FADs on tuna distribution, their vulnerability to fishing gear, and the impact of FADs on their overall well being. To address these issues, we have embarked on a comprehensive investigation of the...