Age, growth, and mortality of gray snapper, Lutjanus griseus, from the east coast of Florida

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Date: Apr. 2001
From: Fishery Bulletin(Vol. 99, Issue 2)
Publisher: National Marine Fisheries Service
Document Type: Article
Length: 5,613 words

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Abstract--Gray snapper, Lutjanus griseus, were sampled from recreational headboat and commercial landings along the east coast of Florida, 1994-97. Fish were weighed (g) and measured (total length, TL, in mm), and sagittal otoliths were removed for aging. Marginal increment analysis on sectioned otoliths (n=1243) confirmed annulus formation in June and July. The oldest fish examined was 24 years old and measured 760 mm TL. Weight-length relations were not significantly different by sex. Weight-length relations were significantly different (F=39.198, P [is less than] 0.001, df=10,705) for fish measured from the headboat survey from 1982-97 between north Florida (W=8.4 x [10.sup.-9] x [TL.sup.3.08], n=4034) and south Florida (W=5.45 x [10.sup.-9] x [TL.sup.3.15], n=6670), where W = total weight (kg). The TL-otolith radius (OR) relationships were described by the following equations: TL = (10.02 x OR) - 52.98 ([r.sup.2]=0.90, n=519, north Florida), and TL = (9.90 x OR) - 91.68 ([r.sup.2]=0.78, n=724, south Florida). Mean lengths at age from back-calculations to the last annulus ranged from 121 mm at the end of age 1 to 740 mm at age 24 for north Florida, and 227 mm at age 2 to 495 mm at age 15 for south Florida. The von Bertalanffy growth equations were [L.sub.t] = 717 x (1 - [e.sup.(-0.17 (t + 0.025))]) for north Florida and [L.sub.t]=625 x (1 - [e.sup.(-0.13 (t + 1.33))]) for south Florida. Estimates of M ranged from 0.14 to 0.43 for north Florida and from 0.29 to 0.38 for south Florida. Estimates of Z averaged 0.34 for north Florida and 0.95 for south Florida. Recruitment to the fisheries occurred between ages 5 and 8 for north Florida and ages 4 and 5 for south Florida. Estimates of F for gray snapper by area were 0.16 for north Florida and 0.66 for south Florida.

The gray snapper, Lutjanus griseus, is a moderate-size (to 8 kg) snapper (Lutjanidae) widely distributed in the western Atlantic from Florida through Brazil, including Bermuda, the Caribbean and the northern Gulf of Mexico (Robins et al., 1986). Juveniles have been reported from as far north as Massachusetts (Sumner et al., 1911), and transforming gray snapper larvae have been caught in ichthyoplankton samples collected at Ocracoke and Oregon Inlets, North Carolina (Hettler and Barker, 1993). Adults are rarely caught in the fisheries of North Carolina; the larvae appear to be Gulf Stream exports and do not survive winter temperatures. Gray snapper occupy a variety of habitats during their life cycle. Adults are found near irregular, complex habitats, such as coral reefs, shipwrecks, rocky outcroppings and ledges, and other natural livebottom areas (Miller and Richards, 1980). Spawning occurs offshore, and eggs and larvae are transported into estuarine, shallow seagrass, and mangrove nursery areas by favorable currents. Larvae, juveniles, and smaller adults are found inshore in seagrass beds and around mangrove thickets, pilings, seawalls, and jetties. While they inhabit inshore areas, these younger fish are subject to fishing pressure from recreational fishermen. After moving offshore between the ages of 3 and 4 (Rutherford et al., 1983),...

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Gale Document Number: GALE|A75434041