Influence of environmental, spatial, and ontogenetic variables on habitat selection and management of spiny dogfish in the Northeast (US) shelf large marine ecosystem

Declines in abundance of commercially valuable groundfish have highlighted the ecological and commercial importance of previously underutilized elasmobranchs in the Northeast (US) shelf large marine ecosystem (NES LME). Seasonal distributions and ontogenetic habitats of one such species, spiny dogfish (Squalus acanthias), were investigated using Northeast Fisheries Science Center (NEFSC) bottom trawl survey data (1963–2009). Neonate, immature, and mature dogfish all selected warmer, more saline, and more southerly locations during spring compared with available locations. During autumn, larger dogfish occupied relatively warmer, shallower, and less saline waters while neonates selected higher salinities. There were strong ontogenetic patterns in habitats occupied. Contrary to expectation, geographic range contracted as abundance increased during autumn. This suggests that niche constraints override density-dependent effects, although detection of relationships within stages was limited by low statistical power. The proportion of mature female survey catch within the Mid-Atlantic Bight was significantly related to temperature, suggesting that environmental conditions surveyed may impact population trends. Collectively, these results highlight critical habitats, suggest mechanisms behind ontogenetic habitat selection, and provide insight into how changing environmental conditions may impact stock assessment.

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Application of generalized additive models to examine ontogenetic and seasonal distributions of spiny dogfish (Squalus acanthias) in the Northeast (US) shelf large marine ecosystem

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0342 ◽

2014 ◽

Vol 71 (6) ◽

pp. 847-877 ◽

Cited By ~ 33

Author(s):

Skyler R. Sagarese ◽

Michael G. Frisk ◽

Robert M. Cerrato ◽

Kathy A. Sosebee ◽

John A. Musick ◽

...

Keyword(s):

Generalized Additive Models ◽

Marine Ecosystem ◽

Additive Models ◽

Squalus Acanthias ◽

Seasonal Occurrence ◽

Spiny Dogfish ◽

Science Center ◽

Large Marine Ecosystem ◽

Northeast Us ◽

The Relationship

Increased commercial importance of spiny dogfish (Squalus acanthias) combined with an often debated, and controversial, ecological impact has warranted an investigation of the relationship among distribution, environment, and prey to better understand the species ecology and inform management. To elucidate mechanisms behind distributional changes, we modeled seasonal occurrence and abundance of neonate, immature, and mature spiny dogfish as functions of abiotic and biotic factors using generalized additive models and Northeast Fisheries Science Center bottom trawl survey data. Significant nonlinear relationships were widespread throughout dogfish stages and seasons. Seasonal occurrence was tightly linked to depth and bottom temperature, with year and Julian day influential for some stages. While these factors also influenced abundance, ecological factors (e.g., squid abundances) significantly contributed to trends for many stages. Potential impacts of climate change were evaluated by forecasting distributions under different temperature scenarios, which revealed higher regional probabilities of occurrence for most stages during a warmer than average year. Our results can be used to better understand the relationship between sampling periods and movement drivers to survey catchability of the population in the Northeast (US) shelf large marine ecosystem.

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Bounds on Biomass Estimates and Energetic Consequences of Ctenophora in the Northeast U.S. Shelf Ecosystem

International Journal of Oceanography ◽

10.1155/2014/851809 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Michael D. Ford ◽

Jason S. Link

Keyword(s):

Feeding Strategy ◽

Marine Ecosystem ◽

High Energy ◽

Gelatinous Zooplankton ◽

Squalus Acanthias ◽

High Energy Density ◽

Spiny Dogfish ◽

Sampling Device ◽

Large Marine Ecosystem ◽

Major Increase

Previous descriptions have noted that the stomach samples of spiny dogfish, Squalus acanthias, showed a major increase in the overall occurrence and hence implied abundance of Ctenophora. This apparent and persistent gelatinous zooplankton outbreak is increasingly more common in the world’s oceans. We briefly explore the energetic ramifications of ctenophores in the spiny dogfish diet, inferring that the presence of gelatinous zooplankton represents an ambient feeding strategy. Relative to other prey, ctenophores are not a high energy density prey item. However, given varying assumptions of the amount of ctenophores consumed, they may be an important staple in the diet of spiny dogfish. We also examine the utility of using spiny dogfish as a gelatinous zooplankton sampling device. Using five calculation methodologies, we provide bounds on potential abundance and biomass estimates of ctenophores in the Northeast U.S. shelf ecosystem. We then contextualize these findings relative to the implications for the Northeast U.S. and any large marine ecosystem.

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Statistical Power of Trends in Fish Abundance

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-232 ◽

1987 ◽

Vol 44 (11) ◽

pp. 1879-1889 ◽

Cited By ~ 35

Author(s):

Randall M. Peterman ◽

Michael J. Bradford

Keyword(s):

Time Trends ◽

Statistical Power ◽

Stock Assessment ◽

Cohort Analysis ◽

Assessment Methods ◽

Trawl Survey ◽

Estimation Errors ◽

Management Objectives ◽

Fish Abundances ◽

Parophrys Vetulus

Estimation errors inherent in stock assessment methods may make it difficult to estimate time trends in fish abundances correctly. Our objective was to quantify the probability that trends in abundance of recruits will be successfully identified. For this analysis, we used an empirically based simulation model of English sole (Parophrys vetulus) off the west coast of North America. The unique wealth of data and past analyses of this population permitted us to include deterministic and stochastic components of growth, mortality, and reproduction in a realistic manner. Errors were also included in two simulated stock assessment methods: a trawl survey and cohort analysis. Under various conditions, we calculated the probability (analogous to statistical power) that these methods will meet three management objectives concerning time trends in recruitment. Monte Carlo simulations showed that although power depends on the objective, under most realistic conditions the probability of correctly detecting recruitment time trends may be unacceptably low. These results suggest new management guidelines for fisheries.

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