Does hook type influence the catch rate, size, and injury of grouper in a North Carolina commercial fishery?

Abstract

Members of the Epinephelinae subfamily of serranids (“grouper”) are heavily exploited by both recreational and commercial hook-and-line fishermen on the continental shelf of the southeastern United States. However, aspects of groupers’ biology and ecology render them extremely vulnerable to overexploitation, including slow growth, late reproduction, large size, and long life span. In addition to direct fishing mortality, hook and release mortalities likely occur when grouper are caught and released, due to injuries sustained from hooking as well as those associated with retrieval from deep waters. Here, we evaluated four hook sizes and styles (5/0 “J”, 7/0 “J”, 9/0 “J”, and 12/0 circle hooks) during the summer of 2003 by their ability to reduce catches of sublegal grouper and non-target species in Onslow Bay, North Carolina, USA. A total of 1249 fish representing 33 species were landed during 20 days of commercial fishing activities. The most common grouper landed were red grouper Epinephelus morio (n = 459), gag grouper Mycteroperca microlepis(n = 55), and scamp grouper Mycteroperca phenax(n = 50). Overall, 6.8% of grouper landed were below the minimum size limit, and the proportion of sublegal grouper caught per day decreased with depth. Catch rates for small grouper (i.e., <50.8 cm fork length), non-target individuals, and sharks varied across hook treatments, while catch rates for large grouper (i.e., ≥50.8 cm fork length) did not. Circle hooks significantly reduced gut hooking in all groupers as well as non-target species. The proportion of grouper and non-target fish that bled varied across hooking locations, with more fish bleeding from gut and gill hooking than jaw hooking. Finally, the proportion of red and gag grouper with distended stomachs was positively related to the water depth in which the fish were caught. These results suggest a tradeoff between fishing in shallow water to reduce depth-related injuries to grouper and fishing in deeper water to minimize the catch of sublegal grouper. © 2004 Elsevier B.V. All rights reserved.