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  • 1
    Online Resource
    Online Resource
    Harvest strategies for climate-resilient fisheries
    Oxford University Press (OUP) ; 2021
    In:  ICES Journal of Marine Science Vol. 78, No. 8 ( 2021-10-27), p. 2774-2783
    Details
    In: ICES Journal of Marine Science, Oxford University Press (OUP), Vol. 78, No. 8 ( 2021-10-27), p. 2774-2783
    Abstract: A pressing challenge for climate-vulnerable fisheries is how to manage now for present and future climate change. In contrast to climate forecasting approaches, we track integrated signals of change for example populations in a climatically forced region and use stochastic dynamic programming to compare the performance of a range of management-ready policies over all possible future states. Our main results highlight: (i) that biomass-linked harvest control rules (HCRs) can partially compensate for changing production, even if the HCR is time invariant; and (ii) that the form of utility (e.g. risk neutral or risk averse) can result in remarkably different optimal decision paths. Performance over future horizons degrades marginally from dynamic HCRs to static HCRs (except at low productivity where differences are more pronounced) but markedly when the biomass level is ignored altogether, as is the case in many managed fish populations globally. Understanding the processes whereby climate affects productivity is important for interpreting past data, but forecasts are not needed for tactical decision making now. Instead, we argue that the priorities for managing fish stocks influenced by climate change are to: measure the current productivity, assess the current abundance of the stock, and respond with a dynamic HCR.
    Type of Medium: Online Resource
    ISSN: 1054-3139 , 1095-9289
    URL: Article
    DOI: 10.1093/icesjms/fsab152
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
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  • 2
    Online Resource
    Online Resource
    Characterisation and monitoring of one of the world's most valuable ecotourism animals, the southern stingray at Stingray City, Grand Cayman
    CSIRO Publishing ; 2018
    In:  Marine and Freshwater Research Vol. 69, No. 1 ( 2018), p. 144-
    Details
    In: Marine and Freshwater Research, CSIRO Publishing, Vol. 69, No. 1 ( 2018), p. 144-
    Abstract: Southern stingrays (Hypanus americanus) represent a multimillion dollar ecotourism operation in Grand Cayman, interacting with over a million visitors annually. Over 30 years of stingray provisioning by tour operators has provided a predictable aggregation at the Stingray City Sandbar (SCS). Despite potentially negative effects of provisioning and concerns about declining stingray numbers at SCS, there has never been a formal assessment of the aggregation. In the present study we analysed tagging data from 2002 to 2015 and established structured censuses monitoring the aggregation. The consistently female-dominated aggregation declined between 2008 and 2012, from 〉 100 to 〈 60 stingrays, but has increased since 2012, stabilising at ~90 stingrays. Female site fidelity was high, with ~20% of females resident for ≥10 years, compared with only 3 years for most males. Stingrays were also found to have growth rates similar to those in captivity. The results of the present study suggest the SCS aggregation is highly dependent on individuals arriving from the island-wide stingray population, susceptible to perturbation, and that successful management of activities at SCS will benefit from regular monitoring of the stingray aggregation. We chronicle the historical status of this well-known and economically valuable marine resource and provide suggestions applicable towards sustainable human–marine wildlife interactions for similar resources.
    Type of Medium: Online Resource
    ISSN: 1323-1650
    URL: Article
    DOI: 10.1071/MF17030
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2018
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    SSG: 21,3
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  • 3
    Online Resource
    Online Resource
    Evaluating the performance of a multispecies statistical catch-at-age model
    Canadian Science Publishing ; 2013
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 70, No. 3 ( 2013-03), p. 470-484
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 70, No. 3 ( 2013-03), p. 470-484
    Abstract: Predation is a substantial source of mortality that is a function of the abundance of predator and prey species. This source of mortality creates a challenge of incorporating species interactions in statistical catch-at-age models in a way that accounts for the uncertainty in input data, parameters, and results. We developed a statistical, age-structured, multispecies model for three important species in the Georges Bank fish community: Atlantic cod (Gadus morhua), silver hake (Merluccius bilinearis), and Atlantic herring (Clupea harengus). The model was fit to commercial catch, survey, and diet data from 1978 to 2007. The estimated predation rates were high, compared with fishing mortality, and variable with time. The dynamics of the three species can be explained by the interplay between fishing and predation mortality. Monte Carlo simulations were used to evaluate the ability of the model to estimate parameters with known error introduced into each of the data types. The model parameters could be estimated with confidence from input data with error levels similar to those obtained from the model fit to the observed data. This evaluation of model performance should help to move multispecies statistical catch-at-age models from proof of concept to functional tools for ecosystem-based fisheries management.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/cjfas-2012-0229
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2013
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  • 4
    Online Resource
    Online Resource
    The occurrence of the colonial ascidian Didemnum sp. on Georges Bank gravel habitat — Ecological observations and potential effects on groundfish and scallop fisheries
    Elsevier BV ; 2007
    In:  Journal of Experimental Marine Biology and Ecology Vol. 342, No. 1 ( 2007-3), p. 179-181
    Details
    In: Journal of Experimental Marine Biology and Ecology, Elsevier BV, Vol. 342, No. 1 ( 2007-3), p. 179-181
    Type of Medium: Online Resource
    ISSN: 0022-0981
    URL: Article
    DOI: 10.1016/j.jembe.2006.10.038
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2007
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    SSG: 7,20
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  • 5
    Online Resource
    Online Resource
    Changes in higher trophic level productivity, diversity and niche space in a rapidly warming continental shelf ecosystem
    Elsevier BV ; 2020
    In:  Science of The Total Environment Vol. 704 ( 2020-02), p. 135270-
    Details
    In: Science of The Total Environment, Elsevier BV, Vol. 704 ( 2020-02), p. 135270-
    Type of Medium: Online Resource
    ISSN: 0048-9697
    URL: Article
    DOI: 10.1016/j.scitotenv.2019.135270
    RVK:
    AR 10100
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
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    detail.hit.zdb_id: 121506-1
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  • 6
    Online Resource
    Online Resource
    U.S. Ocean Fish Recovery: Staying the Course
    American Association for the Advancement of Science (AAAS) ; 2005
    In:  Science Vol. 309, No. 5735 ( 2005-07-29), p. 707-708
    Details
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 309, No. 5735 ( 2005-07-29), p. 707-708
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    URL: Article
    DOI: 10.1126/science.1113725
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2005
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  • 7
    Online Resource
    Online Resource
    Effect of nonlinear predation rates on rebuilding the Georges Bank haddock (Melanogrammus aeglefinus) stock
    Canadian Science Publishing ; 1997
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 54, No. 12 ( 1997-12-01), p. 2920-2929
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 54, No. 12 ( 1997-12-01), p. 2920-2929
    Abstract: The collapse of several northwest Atlantic groundfish stocks, including Georges Bank haddock (Melanogrammus aeglefinus), necessitated new fishing regulations and generated interest in the role of predation on stock productivity. The sharp break between prolonged periods of high (pre-1965) and low (post-1965) haddock abundance suggests differing levels of stock productivity, consistent with a surplus production model incorporating a nonlinear predation rate (Steele and Henderson's (1984. Science (Washington, D.C.), 224: 985-987) model). This model and a Schaefer (1957. Inter-Am. Trop. Tuna Comm. Bull. 2: 245-285) model without a predation term were fit to haddock data to evaluate various rebuilding strategies with two performance measures: the sums of discounted yield and discounted revenue. Steele and Henderson's model provided plausible parameter estimates for the entire data set (1931-1993) whereas Schaefer's model provided plausible estimates only for years of low productivity (1976-1993). The presence of multiple equilibria in Steele and Henderson's model resulted in minor shifts of F, potentially producing large shifts in projected future biomass. For either model, levels of F that maximize either yield or revenue were lower than the recently adopted target level of F 0.1 = 0.24. Recent low production provides impetus for managers to consider a variety of plausible stock production models, and the uncertainty of production dynamics, in choosing rebuilding strategies.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/f97-197
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1997
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  • 8
    Online Resource
    Online Resource
    Detecting population regulation of winter flounder from noisy data
    Canadian Science Publishing ; 2022
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 79, No. 7 ( 2022-07), p. 1097-1108
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 79, No. 7 ( 2022-07), p. 1097-1108
    Abstract: Year-class size of marine fish is thought to be determined during the first year of life, with density-dependent mortality occuring during the larval or juvenile stages. However, investigations of such dynamics are often limited by data availability. To test this paradigm for winter flounder (Pseudopleuronectes americanus) in Narragansett Bay, Rhode Island, the abundances of 29 year classes moving through seven life stages were analyzed with a novel extension of key-factor analysis. Evidence of density dependence was identified between the egg and July young-of-the-year stages and high process-error variance was detected throughout the life cycle, suggesting year-class size is not fully determined until age-2. However, the first summer appeared to be a critical life stage for winter flounder, during which high temperatures, hypoxia, and predator abundance contributed to increased mortality rates behind a long-term population decline. Due to its general data requirements, the key-factor analysis method developed here may be applied to other aquatic populations to identify the impacts of external stressors at particular life stages and the degree to which they are compensated by density-dependent processes.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/cjfas-2021-0004
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2022
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    SSG: 21,3
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Biological reference points for fish stocks in a multispecies context
    Canadian Science Publishing ; 2001
    In:  Canadian Journal of Fisheries and Aquatic Sciences Vol. 58, No. 11 ( 2001-11-01), p. 2167-2176
    Details
    In: Canadian Journal of Fisheries and Aquatic Sciences, Canadian Science Publishing, Vol. 58, No. 11 ( 2001-11-01), p. 2167-2176
    Abstract: Biological reference points (BRPs) are widely used to define safe levels of harvesting for marine fish populations. Most BRPs are either minimum acceptable biomass levels or maximum fishing mortality rates. The values of BRPs are determined from historical abundance data and the life-history parameters of the fish species. However, when the life-history parameters change over time, the BRPs become moving targets. In particular, the natural mortality rate of prey species depends on predator levels; conversely, predator growth rates depend on prey availability. We tested a suite of BRPs for their robustness to observed changes in natural mortality and growth rates. We used the relatively simple Baltic Sea fish community for this sensitivity test, with cod as predator and sprat and herring as prey. In general, the BRPs were much more sensitive to the changes in natural mortality rates than to growth variation. For a prey species like sprat, fishing mortality reference levels should be conditioned on the level of predation mortality. For a predator species, a conservative level of fishing mortality can be identified that will prevent growth overfishing and ensure stock replacement. These first-order multispecies interactions should be considered when defining BRPs for medium-term (510 year) management decisions.
    Type of Medium: Online Resource
    ISSN: 0706-652X , 1205-7533
    URL: Article
    DOI: 10.1139/f01-158
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2001
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    detail.hit.zdb_id: 1473089-3
    SSG: 21,3
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  • 10
    Online Resource
    Online Resource
    ASSESSING UNCERTAINTY IN A MULTISPECIES AGE‐STRUCTURED ASSESSMENT FRAMEWORK: THE EFFECTS OF DATA LIMITATIONS AND MODEL ASSUMPTIONS
    Wiley ; 2015
    In:  Natural Resource Modeling Vol. 28, No. 2 ( 2015-05), p. 184-205
    Details
    In: Natural Resource Modeling, Wiley, Vol. 28, No. 2 ( 2015-05), p. 184-205
    Abstract: Performance of a multispecies age‐structured assessment (MSASA) model in the Gulf of Alaska (GOA) relative to changes in data and model assumptions was examined through simulation exercises. Species included arrowtooth flounder ( Atheresthes stomias ), Pacific cod ( Gadus macrocephalus ), walleye pollock ( Theragra chalcogramma ), Pacific halibut ( Hippoglossus stenolepis ), and Steller sea lion ( Eumetopias jubatus ). Age‐specific predation mortality was estimated as a flexible function of predator and prey abundances and fitted to diet data. Simulated data sets were constructed by applying random error to estimates of catch, survey, and diet data from an operating model, whose structure was identical to that of the estimating model. Simulations explored the effects of data variability, mismatched assumptions regarding model structure, and lack of diet data on model performance. Model misspecification and uninformative diet data had the greatest influence on model performance. Given the current emphasis on the development of ecosystem‐based models and management, prioritizing the rigorous sampling of diet data would best facilitate the development of predation models useful to management agencies.
    Type of Medium: Online Resource
    ISSN: 0890-8575 , 1939-7445
    URL: Issue
    URL: Article
    DOI: 10.1111/nrm.2015.28.issue-2
    DOI: 10.1111/nrm.12063
    Language: English
    Publisher: Wiley
    Publication Date: 2015
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    SSG: 11
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