Effects of release parameters on recovery rates of tagged groundfish species

Abstract

A compilation of groundfish mark-recapture studies conducted in the Northwest Atlantic from 1953 to 1985 was examined by analysis of deviance to determine the effects of release parameters on subsequent recoveries of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), pollock (Pollachius virens), and American plaice (Hippoglossoides platessoides). Fish length was a major determinant of recoveries for all four species, with recovery rates generally increasing with increasing fish length. Depth of capture was a significant determinant of recoveries for cod and haddock, with recovery rates decreasing as depth increased. Year of release was a significant determinant for all four species, with recovery rates declining in recent years. Declines in recovery rates of cod, haddock, and pollock occurred during certain months or seasons. Recovery rates decreased where fish were tagged in areas most distant from inhabited coastal regions, but the interpretation of this effect is complicated by changes in the fisheries over time between areas. Recovery rates also decreased with increasing catch size and varied between different tag types and capture methods. The results should prove useful in the design of tagging protocols and analysis of recovery data.

Characteristics of spawning ground fidelity by a diadromous fish: a multi-year perspective

“…Although the recapture rate in this study was not high, it was similar to other studies that used internal tags and required physical recapture of marine fishes (e.g., Leber et al 1995;Willis et al 1995) as well some using external tags (e.g., Fowler and Stobo 1999). Furthermore, it is common knowledge that snook move between estuarine habitats and spawning grounds during spawning season, which likely contributed to the relatively low overall recapture rate in that this study sampled only a portion of the overall local population.…”

Movements and growth of monkfish Lophius piscatorius tagged at the Shetland Islands, northeastern Atlantic

“…This finding is in contrast to that for some other species. For example, Fowler and Stobo (1999) reported that for each of Atlantic cod, haddock, pollock (Pollachius virens) and American plaice (Hippoglossoides platessoides), the length at release was a significant factor in the subsequent recovery rates, with recoveries generally being higher for fish with larger sizes at release.…”

Spawning site fidelity in Baltic Sea turbot (Psetta maxima)

“…In addition the mean size of recaptured fish was slightly larger than the mean size of turbot in the concurrently sampled commercial gill net fishery. Body length has previously been shown to be the major determinant of recovery rate in tagged ground fish, including flatfish (Fowler and Stobo, 1999). There are four different, not mutually exclusive, explanations for this pattern.…”

“…If there is competition among fish for spawning sites, it is possible that larger fish can remain at favored sites while smaller individuals are banished to less favorable areas and are less likely to be recaptured. The variation in recovery rate that was seen between years is common in tagging experiments (Fowler and Stobo, 1999) and could most easily be explained by temporal differences in fishing effort and pattern.…”