Virginia Institute of Marine Science
MARINE AND COASTAL FISHERIES
This study examines the potential uncertainty in survey biomass estimates of Spiny Dogfish Squalus acanthias in the Northeast U.S. Continental Shelf Large Marine Ecosystem (NES LME). Diel catch-per-unit-effort (CPUE) estimates are examined from the Northeast Fisheries Science Center bottom trawl surveys conducted during autumn (1963-2009) and spring (1968-2009). Influential environmental variables on survey catchability are identified for Spiny Dogfish life history stages and five pelagic prey species: Butterfish Peprilus triacanthus, Atlantic Herring Clupea harengus, shortfin squid Illex spp., longfin squid Doryteuthis spp., and Atlantic Mackerel Scomber scombrus. Daytime survey catchability was significantly higher than nighttime catchability for most species during autumn and for mature male Spiny Dogfish, shortfin squid, and longfin squid during spring in the NES LME. For most stages and species examined, breakpoint analyses identified significant increases in CPUE in the morning, peak CPUE during the day, and significant declines in CPUE in the late afternoon. Seasonal probabilities of daytime catch were largely driven by solar zenith angle for most species, with stronger trends identified during autumn. Unadjusted CPUE estimates appear to overestimate absolute abundance, with adjustments resulting in reductions in absolute abundance ranging from 41% for Spiny Dogfish to 91% for shortfin and longfin squids. These findings have important implications for Spiny Dogfish regarding estimates of population consumption of key pelagic prey species and their ecological footprint within the NES LME.
GENERALIZED ADDITIVE-MODELS; BOTTOM-TRAWL SURVEYS; GEORGES-BANK; DIURNAL-VARIATION; VERTICAL MIGRATION; NORTHWEST ATLANTIC; SQUALUS-ACANTHIAS; FISH; COMMUNITY; ABUNDANCE
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This work is licensed under a Creative Commons Attribution 4.0 License.
The authors thank all those individuals who have worked or volunteered aboard the NOAA RV Albatross IV and RV Henry B. Bigelow, Woods Hole, Massachusetts, for assistance with survey data collection. Two anonymous reviewers also helped improve the quality of this manuscript. This project was funded by the National Marine Fisheries Service Sea Grant Fellowship in Population Dynamics.
Sagarese, Skyler R.; Frisk, Michael G.; Cerrato, Robert M.; Sosebee, Kathy A.; and Musick, John A., "Diel Variations in Survey Catch Rates and Survey Catchability of Spiny Dogfish and their Pelagic Prey in the Northeast US Continental Shelf Large Marine Ecosystem" (2016). VIMS Articles. 36.