Age, Growth, and Mortality of Wahoo, Acanthocybium solandri, from the Atlantic coast of Florida and the Bahamas

 

Richard S. McBride1, Adam K. Richardson, and Kristin L. Maki2

 

Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, 100 8th Ave SE, St. Petersburg, FL 33701

 

1Present address: NOAA Fisheries, Northeast Fisheries Science Center, 166 Water Street, Woods Hole MA 02543, richard.mcbride@noaa.gov

2Present address: PBS&J 5300 W. Cypress Suite 200, Tampa, FL 33607,

klmaki@pbsj.com

 

Abstract

This study examined wahoo, Acanthocybium solandri, collected year-round from waters offshore of Florida’s east coast to investigate this species’ size, age, growth, and mortality. Wahoo ranged in size from 628 to 1956 mm fork length (FL; n = 575). Except that the largest individuals were female, there was no evidence of sexual dimorphism nor that sex ratio differed from 1:1. This study presents an edge analysis to support the use of sectioned otoliths for ageing wahoo. Annuli were formed during winter-spring. Wahoo were short lived (median = 1.5 years, mean = 1.9, maximum = 9.2, n = 469) and had a high mortality rate (Z = 0.86). They grew rapidly and to a large size; von Bertalanffy growth parameters were: L∞ = 1798 mm fork length [FL], K = 0.240, to = -2.82. Females had a very similar maximum age relative to males (maximum age 9.2 v. age 9.0 years); females also grew modestly larger (L∞ = 1937 v. 1617 mm FL, maximum observed = 1804 v. 1570 mm FL) and had slightly lower mortality (Z = 0.80 v. 0.94) than males. These sex-specific differences were not statistically significant. Published reports of comparable demographics demonstrate no markedly different life history parameters for wahoo elsewhere in the western Atlantic Ocean.

 

 

Reproductive Biology of Wahoo, Acanthocybium solandri, from the Atlantic coast of Florida and the Bahamas

 

By Kristin L. Maki1 and Richard S. McBride2

Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, 100 8th Ave SE, St. Petersburg, FL 33701

 

1Present address: PBS&J 5300 W. Cypress Suite 200, Tampa, FL 33607, klmaki@pbsj.com

2Present address: NOAA Fisheries, Northeast Fisheries Science Center, 166 Water Street, Woods Hole MA 02543, richard.mcbride@noaa.gov

 

ABSTRACT – Wahoo, Acanthocybium solandri, were collected from the Atlantic coast of Florida and in the northern Bahamas during 1997-2006 to examine oocyte development, maturation, reproductive seasonality, spawning frequency, and annual fecundity. Examination of gonad histology revealed that oocyte development was asynchronous and oocyte atresia was common during the spawning season; thus, fecundity was indeterminate. The smallest mature female was 880 mm FL, the largest immature female was 1150 mm FL. The size and age at 50% female maturity was 925 mm FL and 1.3 years, respectively. Wahoo were summer spawners: gonadosomatic indices of both sexes and the percent frequency of mature, active females were elevated from May to August.  The year-round samples available here did not find evidence of spring spawning as postulated by an earlier study of wahoo in the western North Atlantic and Gulf of Mexico. Some mature but inactive fish were found during the summer spawning season, which may be evidence for skip spawning or asynchronous spawning patterns among individuals. Wahoo are batch spawners, with a median spawning frequency of once every five days during May-August. Batch fecundity was positively correlated with fish size, varying between 0.44 and 1.67 million eggs. Although wahoo have been noted to have relatively small gonads, annual fecundity estimates are not small: on the order of 10-100 million eggs.