Steven Cadrin - Academia.edu (original) (raw)

Papers by Steven Cadrin

Fisheries Research, Dec 1, 2008

Elements of the precautionary approach to fishery management are commonly implemented in the form... more Elements of the precautionary approach to fishery management are commonly implemented in the form of harvest control rules, with limit, threshold and target reference points for stock size and fishing mortality. However, a review of two large advisory and management systems indicates that many stock assessments are not sufficiently informative to support such control rules. After a nearly a decade of applying such control rules, a large portion of management units in the International Council for the Exploration of the Sea (ICES) convention and marine fisheries under United States jurisdiction still have uncertain status, because many management units lack a complete suite of fishing mortality and biomass estimates and associated reference points. For those fishery resources with analytical stock assessments and reference point estimates, fishing mortality has generally been reduced to within prescribed limits. The number of stocks in the ICES area with excessive fishing mortality (i.e., greater than the limit reference point) decreased since 1997, but the number of stocks in need of rebuilding increased as a result of excessive fishing or revised reference points. The number of U.S. stocks with excessive fishing decreased and the number of stocks needing rebuilding decreased as a result of stock recovery, revised reference points, or redefined management units. The number of U.S. stocks with uncertain or undefined status substantially decreased. The large portion of stocks with uncertain status in both systems illustrates that such precautionary control rules are applied only to data-rich stock assessments, and are not being applied to management of fishery resources with the most uncertain stock assessments. Published by Elsevier B.V. "The absence of scientific information should not be used as a reason for postponing or failing to take conservation and management measures" (FAO Code of Conduct for Responsible Fisheries, 1995a).

Wiley-Blackwell eBooks, May 27, 2009

Human Ecology, Feb 2, 2010

Considering the general state of our natural resources and many inefficient regulations, we often... more Considering the general state of our natural resources and many inefficient regulations, we often wonder, "How did we get into such a mess?" The easiest response is to blame irresponsible stakeholders or corrupt management. Adaptive Governance: the dynamics of Atlantic Fisheries Manage ment offers a more constructive perspective on the topic, with a focus on the historical development of international regulations for managing highly migratory fish species (tuna, swordfish and marlin). If fishery regulations are viewed as a finished product, their complexity and inconsistency can be confusing. However, if governance of fisheries is considered to be adaptive (i.e., developed and improved over time), these inconsistencies become under standable, and even predictable. Webster applies her skills as a social scientist to an in depth analysis and thought-provoking interpretations. The strength of the book is a view of the current set of inconsistent regulations as predictable results of logical behaviors among competing interests. Adaptive Gover nance recognizes that the historical development of fishery regulations often do not fit the expectations of bioeconomic theory, but conform better with 'satisficing' (a blend of satisfying and sufficing) from decision theory. From this alternative perspective, dissatisfaction, delayed manage ment and compromise are viewed as essential precursors to effective resource management, turning the typical 'blame game' on its ear. Although the title suggests a broad review of North Atlantic fisheries, Webster's analysis is limited to the

Ices Journal of Marine Science, Sep 17, 2019

Atlantic halibut are a "Species of Concern" in US waters and little is known about their movement... more Atlantic halibut are a "Species of Concern" in US waters and little is known about their movements and stock structure. Recent stock assessments drew attention to the paucity of information for assessing and managing this stock. To investigate movement patterns and stock structure, halibut were tagged off Massachusetts and Maine within US waters of the Gulf of Maine region using pop-up satellite archival tags and data storage tags. A hidden Markov model (HMM) geolocation method previously developed for other groundfish species was adapted to estimate the movement tracks of the tagged halibut (n ¼ 25) based on the tag-recorded depth and temperature. Total distance travelled based on geolocation ranged from 36 to 1701 km, whereas straight line distance between tagging and end locations ranged from 0.4 to 440.7 km. Estimated movement rates varied between 2.7 and 10 km day À1. Two tagged halibut made long-distance movements to putative spawning habitat in the Northeast Channel off Georges Bank. Thirteen (13) out of 25 geolocated individuals were estimated to have reached Canadian waters. Geolocation results revealed home range, return movement, and seasonal migration movement patterns exhibited by the tagged halibut. The HMM geolocation method could be a useful tool in providing information on halibut movements that can inform stock assessment and management decisions.

144th Annual Meeting of the American Fisheries Society, Aug 21, 2014

Fishery Bulletin, Sep 30, 2014

Ices Journal of Marine Science, Apr 18, 2013

The distribution of Atlantic mackerel (Scomber scombrus) during their spring migration along the ... more The distribution of Atlantic mackerel (Scomber scombrus) during their spring migration along the Mid-Atlantic Bight and into the Gulf of Maine has historically been associated with spring warming along the continental shelf. Variations in mackerel distributions based on National Marine Fisheries Service spring surveys were compared with variations in sea surface temperature (SST) from satellite remote sensing for the eastern US continental shelf for the period 1985-1999. The mackerel stock was first analysed as a unit, then separated into three size classes to assess differences in distribution among years and individuals of various lengths. Results showed an across-shelf correlation between catch and March SST in the Mid-Atlantic Bight for both the entire population and each size class. Along-shelf catch variations were correlated with SST for large mackerel, but not total stock or smaller size classes. Finally, the distribution of mackerel length in the Gulf of Maine was negatively correlated with March SST in the Great South Channel. Results suggest surface temperature along the northeast continental shelf may be used to predict certain, but not all, aspects of annual migration along the shelf, and that factors in addition to temperature are also important in controlling distributions of Atlantic mackerel.

Elsevier eBooks, 2005

Publisher Summary Patterns of morphometric variation in fishes indicate differences in growth and... more Publisher Summary Patterns of morphometric variation in fishes indicate differences in growth and maturation rates because body form is a product of ontogeny. Morphometric landmark methods comprise one of the two major categories of orphometric analysis, the other being outline methods. In the context of interdisciplinary stock identification, or the use of information from various approaches, morphometric analysis provides information on phenotypic stocks, groups of individuals with similar growth, mortality, and reproductive rates. The phenotypic stock definition is less conservative than the genetic stock definition because it allows for some mixing among stocks, but partial isolation is enough that geographic differences persist. Despite dependence on the environment, ontogenetic rates influence many population attributes (e.g., reproduction, fecundity, longevity, size structure) that are intimately related to population dynamics (intrinsic rate of increase, carrying capacity, productivity, resilience, and so on) and determine how each stock responds to exploitation. Therefore, for the purpose of fishery stock assessment, groups with different growth or reproductive dynamics should be modeled and managed separately, regardless of genetic homogeneity. This chapter reviews common protocols for sampling, analyzing, and interpreting variation associated with morphometric landmarks for stock identification applications.

North American Journal of Fisheries Management, Mar 4, 2014

AbstractMany stocks of Atlantic Cod Gadus morhua have been depleted due to interactions between o... more AbstractMany stocks of Atlantic Cod Gadus morhua have been depleted due to interactions between overfishing and environmental variation. Stock declines were often accompanied by reductions in spawning diversity and collapses of population structure. Studying Atlantic Cod spawning activity can provide insights into the mechanisms involved in rebuilding. This paper reviews the existing literature on Atlantic Cod spawning dynamics, including habitat, timing, behavior, gamete production, larval survivorship, and fishery impacts. The associated implications for fisheries management are discussed, and critical information gaps are identified for inclusion in future research. Of primary importance for consideration by fisheries managers are the spatial and temporal extent of spawning, the behavior of spawners, and the reproductive contributions of older age-classes. The application of spawning closures as part of a multidisciplinary approach to fisheries management is advocated to prevent the disruption of spawn...

Springer eBooks, Feb 5, 2009

Stock identification has been an important prerequisite for stock assessment throughout its histo... more Stock identification has been an important prerequisite for stock assessment throughout its history. The earliest evaluations of recruitment variability recognized that understanding the spatial scale of a fishery resource is essential for studying population dynamics. A paradigm of stock structure was based on closed migration circuits and geographic variation of phenotypic traits and formed a premise for fishery modeling conventions in the mid-1900s. As genetic techniques developed in the late 1900s, the "stock concept" was refined to include a degree of reproductive isolation. Realization that there was no single method that addressed the various assumptions of stock assessment and needs of fishery management prompted a more holistic view of population structure that called for multiple sources of demographic and genetic data. Recent applications of advanced techniques challenge the traditional view of populations as geographically distinct units with homogeneous vital rates and isolation from adjacent resources. More complex concepts such as metapopulations and "contingent theory" may be more applicable to many fishery resources with sympatric population structure. These more complex patterns of population structure have been incorporated into some advanced stock assessment techniques and metapopulation models that account for movement among areas and sympatric heterogeneity. Wider application of spatially explicit models in future stock assessments will require clear identification of stock components, evaluating movement rates and determining the degree Chapter 22

AFS 142nd Annual Meeting, Aug 22, 2012

11 s., 2009

Georges Bank haddock is a recently recovered fish stock in the New England groundfish fishery. Du... more Georges Bank haddock is a recently recovered fish stock in the New England groundfish fishery. Due to federal constraints under the Magnuson-Steven Act, however, this stock cannot be optimally exploited due to the bycatch of other critical species in the New England groundfishery such as cod and yellowtail flounder which are overfished. The Ruhle trawl and Separator trawl are examples of recent advances in gear technology that have been shown to significantly increase haddock to bycatch ratios. This study models the groundfish fishery through a mixed stock yield model which incorporates technological interactions. We also develop a socioeconomic model that quantifies the amount of employment and producer surplus associated with three trawl types. Our results explore policy situations regarding the use of the new trawls. By bridging the biological and socioeconomic models, we are able to view the fishery as a system that more accurately represents stakeholder views. Our model shows that each trawl, when used exclusively, produces different optimum strategies and therefore an optimum management strategy would most likely include a combination of trawl types. Our results also support the logic of using modified trawls for haddock fishing trips in which bycatch is strictly regulated as the Ruhle trawl is able to maintain 80% of catches caught by a conventional trawl while reducing bycatch up to over 60%. This paper is a first step towards an aid for policy makers to examine fishery gear trade-offs and the resulting biological and socioeconomic consequences of different management actions within the constraints of the Magnuson-Stevens Act.

v INTRODUCTION 1 Management History 1 Assessment History 2 FISHERY DATA 3 Commercial Landings 3 D... more v INTRODUCTION 1 Management History 1 Assessment History 2 FISHERY DATA 3 Commercial Landings 3 Discarded Catch 4 ABUNDANCE AND BIOMASS INDICES 5 Stock Abundance and Biomass Indices 5 MORTALITY AND STOCK SIZE 5 Virtual Population Analysis 5 Biomass Dynamics 6 Biological Reference Points 6 Projections 7 DISCUSSION 7 ACKNOWLEDGMENTS 8 REFERENCES 8