Age, growth, and spawning season of red bream (Beryx decadactylus) off the southeastern United States

Red bream (Beryx decadactylus) is a commercially important deep-sea benthopelagic fish with a circumglobal distribution on insular and continental slopes and seamounts. In the United States, small numbers are caught incidentally in the wreckfish (Polyprion americanus) fishery which operates off the southeastern coast, but no biological information exists for the management of the U.S. red bream population. For this study, otoliths (n=163) and gonads (n=161) were collected from commercially caught red bream between 2003 and 2008 to determine life history parameters. Specimens ranged in size from 410 to 630 mm fork length and were all determined to be mature by histological examination of the gonads. Females in spawning condition were observed from June through September, and reproductively active males were found year-round. Sectioned otoliths were difficult to interpret, but maximum age estimates were much higher than the 15 years previously reported for this species from the eastern North Atlantic based on whole-otolith analysis. Estimated ages ranged from 8 to 69 years, and a minimum lifespan of 49 years was validated by using bomb radiocarbon dating. Natural mortality was estimated at 0.06/yr. This study shows that red bream are longer lived and more vulnerable to overfishing than previously assumed and should be managed carefully to prevent overexploitation.

Patterns of growth, mortality, and size of the tropical damselfish Acanthochromis polyacanthus across the continental shelf of the Great Barrier Reef

Age-based analyses were used to demonstrate consistent differences in growth between populations of Acanthochromis polyacanthus (Pomacentridae) collected at three distance strata across the continental shelf (inner, mid-, and outer shelf) of the central Great Barrier Reef (three reefs per distance stratum). Fish had significantly greater maximum lengths with increasing distance from shore, but fish from all distances reached approximately the same maximum age, indicating that growth is more rapid for fish found on outer-shelf reefs. Only one fish collected from inner-shelf reefs reached >100 mm SL, whereas 38−67% of fish collected from the outer shelf were >100 mm SL. The largest age class of adult-size fish collected from inner and mid-shelf locations comprised 3−4 year-olds, but shifted to 2-year-olds on outer-shelf reefs. Mortality schedules (Z and S) were similar irrespective of shelf position (inner shelf: 0.51 and 60.0%; mid-shelf: 0.48 and 61.8%; outer shelf: 0.43 and 65.1%, respectively). Age validation of captive fish indicated that growth increments are deposited annually, between the end of winter and early spring. The observed cross-shelf patterns in adult sizes and growth were unlikely to be a result of genetic differences between sample populations because all fish collected showed the same color pattern. It is likely that cross-shelf variation in quality and quantity of food, as well as in turbidity, are factors that contribute to the observed patterns of growth. Similar patterns of cross-shelf mortality indicate that predation rates varied little across the shelf. Our study cautions against pooling demographic parameters on broad spatial scales without consideration of the potential for cross-shelf variabil

Growth and seasonal recruitment of Octopus maya on Campeche Bank, Mexico

A study of growth and seasonal recruitment of the cephalopod Octopus maya on Campeche Bank, Mexico, was conducted, based on catch at size data sampled from 1983 to 1988. The parameters of a seasonally oscillating version of the von Bertalanffy growth function and total mortality estimates were obtained via the ELEFAN software. It was found that when recruitment occurs early in the year, the growth curve of the next year does not display seasonal oscillations, and conversely. Total mortality estimates ranged from Z = 2.6 to Z = 6.3/year.

Effects of photoperiod on growth of larvae and juveniles of the anemonefish Amphiprion melanopus

Rearing of anemonefishes is now relatively routine compared to the culture of cardinalfishes (Apogonidae) or angelfishes (Pomacanthidae). However, it is still a labor intensive, time intensive and expensive procedure. To reduce time and cost of rearing anemonefishes, experiments were undertaken to improve the methods for rearing Amphiprion melanopus. These experiments were conducted to determine the effect of the length of photoperiod on larval duration, growth to metamorphosis and early juvenile phase. Growth of larvae was significantly faster and the duration of the larval phase was significantly shorter, under a photoperiod of 16 hours light/8 hours dark, compared to the photoperiods of 12 hours light/12 hours dark and 24 hours light/0 hours dark.

On the growth, mortality and recruitment of the spiny lobster (Panulirus homarus) in Sri Lankan waters

Monthly length-frequency data of spiny lobster Panulirus homarus collected from the south coast of Sri Lanka during 1988-1990 were analyzed to estimate von Bertallanfy growth parameters. The asymptotic lengths estimated using Wetherall plots were 322 mm and 315 mm total length for the males and females, respectively. Using o' values of 3.53 for males and 3.61 for females, the growth constant (K) was estimated as 0.21 year super(1) and 0.27 year super(1) for the males and females, respectively. The estimates of natural and total mortality (M and Z) are 0.98 year super(1), 1.96 year super(1) for males and 0.92 year super(1), 1.54 year super(1) for females respectively. Recruitment appears to occur in two pulses per year.

Growth, mortality and recruitment of Nile perch Lates niloticus (L. Centropomidae) in the Nyanza Gulf of Lake Victoria: an evaluation update

A reassessment of the estimates of growth, mortality and recruitment patterns of Nile Perch, Lates niloticus was made based on data from commercial landings collected during the Catch Assessment Survey Programme. Two sets of length frequency data, one each from beach seining and hook and line fisheries, were analyzed. Values of L8 = 169 and 230 (cm TL) and K= 0.18 yr-1 and 0.195 yr-1 were obtained. The total mortality estimates from the catch curve analysis were Z = 0.72 yr-1 and 0.94 yr-1, respectively, with a natural mortality M of about 0.35 for a mean environmental temperature of 27oC. The highest peak for recruitment was in November, December and January with a minor one in June, indicating recruitment of two cohorts per year. These results are discussed and compared to previously available information on L. niloticus in Lake Victoria.

Growth, mortality and recruitment of Omani abalone (Haliotis mariae)

Historical length-frequency data of Oman abalone (Haliotis mariae) from two areas (Sadh and Hadbin) of the Dhofar coast of the Sultanate of Oman were used to estimate growth parameters by nonlinear least square fitting. The results were verified using the ELEFAN I program and then combined to calculate total mortality (Z) and recruitment patterns. The growth parameters values with combined sexes were L sub( infinity ) = 137 mm shell length (SL), K = 0.75 year super(1) and 1.57 year super(1) on Sadh male and female, respectively. The female Z value in Hadbin was 1.55 year super(1) in 1989/90. The 1991 Z value for combined sexes were 2.37 year super(1) in Sadh and 1.66 year super(1) in Hadbin, showing much higher fishing pressure in recent years. There were two recruitment pulses, a major one in January and a minor one in May.