Abstract

Catch rates from fishery-independent surveys often are assumed to vary in proportion to the actual abundance of a population, but this approach assumes that the catchability coefficient (q) is constant. When fish accumulate in a gear, the rate at which the gear catches fish can decline, and, as a result, catch asymptotes and q declines with longer fishing times. We used data from long-term trap surveys (1990-2011) in the southeastern U.S. Atlantic to determine whether traps saturated for 8 reef fish species because of the amount of time traps soaked or the level of fish accumulation (the total number of individuals of all fish species caught in a trap). We used a delta-generalized-additive model to relate the catch of each species to a variety of predictor variables to determine how catch was influenced by soak time and fish accumulation after accounting for variability in catch due to the other predictor variables in the model. We found evidence of trap saturation for all 8 reef fish species examined. Traps became saturated for most species across the range of soak times examined, but trap saturation occurred for 3 fish species because of fish accumulation levels in the trap. Our results indicate that, to infer relative abundance levels from catch data, future studies should standardize catch or catch rates with nonlinear regression models that incorporate soak time, fish accumulation, and any other predictor variable that may ultimately influence catch. Determination of the exact mechanisms that cause trap saturation is a critical need for accurate stock assessment, and our results indicate that these mechanisms may vary considerably among species.

Published in

Fishery Bulletin
2013, Volume: 111, number: 3, pages: 218-232
Publisher: NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE

SLU Authors

• Bartolino, Valerio

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    
  • University of Gothenburg

UKÄ Subject classification

Fish and Wildlife Management


Publication identifier

DOI: https://doi.org/10.7755/FB.111.3.2

Permanent link to this page (URI)

https://res.slu.se/id/publ/54572