Open AccessTrends in Atlantic Contribution to Mixed‐Stock King Mackerel Landings in South Florida Inferred from Otolith Shape Analysis
Author(s) -
Shepard Katherine E.,
Patterson William F.,
De Vries Douglas A.
Publication year - 2010
Publication title -
marine and coastal fisheries
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 28
ISSN - 1942-5120
DOI - 10.1577/c09-014.1
Subject(s) - otolith , fishing , scombridae , stock (firearms) , fishery , geography , oceanography , atlantic multidecadal oscillation , climatology , geology , sea surface temperature , biology , tuna , fish <actinopterygii> , archaeology
The Atlantic Ocean and Gulf of Mexico (GOM) stocks of king mackerel Scomberomorus cavalla are genetically distinct but have overlapping winter ranges around South Florida. Understanding the factors driving the relative contribution of each stock to South Florida winter landings is necessary for effective management. The contribution of the Atlantic stock was estimated for the 2006–2007 and 2007–2008 fishing seasons using otolith shape as a natural tag. Analysis of otolith shapes from king mackerel sampled in summer (when the Atlantic and GOM stocks were presumed to be geographically separated) revealed significant sex and stock effects. Discriminant function analysis conducted with otolith morphometric indices and Fourier harmonic amplitudes as classification variables produced jackknifed classification success rates ranging from 60% to 73%. Maximum likelihood estimates of the Atlantic stock's contribution to winter landings indicated that there was a spatial gradient, the lowest contribution (mean = 25%) occurring off southwestern Florida and the highest (mean = 48%) off southeastern Florida. Estimates of the Atlantic stock's contribution to the easternmost zone increased from December through March, possibly reflecting the northward spring migration of both stocks. A comparison of contemporary and historic estimates dating back to the 1996–1997 fishing season revealed evidence of a long‐term increase in the GOM stock's contribution, which may be driven by a dramatic increase in the size of the GOM stock and a gradual decline in that of the Atlantic stock over the time period considered.