Spawning stock dynamics of two penaeid prawns, Metapenaeus bennettae and Penaeus esculentus, in Moreton Bay, Queensland, Australia

Abstract

ABSTRACT. Spawning stock dynamics of 2 commercially important penaeid prawns, Metapenaeus bennettae and Penaeus esculentus, from 9 stations in Moreton Bay (27" 15'S, 153'15'E), southeast Queensland, Australia, were examined. An egg production index (EPI), based on the relative abundance, proportion that were mature or ripe, and s u e of adult females, was used as a measure of e g g production in the 2 populations. Egg production by M. bennettae was 20 to 30 higher than that by P esculentus, extended over 7 to 8 mo each year and peaked from February to March (late summer to early autumn). Monthly patterns in egg production by M. bennettaevaried between years. In contrast, P esculentiis produced most of its eggs in a single, clearly defined peak in Octobcr (spring), although production continued to March (early autumn) each year The seasonal onset and subsequent decline in maturation In P esculentus were r a p~d .Egg production by M. bennettae was several times higher at the 5 northern statlons than at the 4 southern stations and negatively correlated with salinity during the main spawning p e r~o d .Egg production by P esculentus was less varied among stations and positively correlated with depth. P esculentus appeared more likely than M. bennettae to experience recruitment overfishing because (1) the peak spawning period for F! esculentus was dependent on relatively few adult females spawning over a short period, and (2) the selectivity of trawl nets used in the bay was much higher for P esculentus spawners than for those of M. bennettae Compared with more northern populations, P esculentus in Moreton Bay matured a t a larger size, had lower inc~dences of insemination and mature or ripe females, and had a shorter spawning period. These results suggest the likelihood of recruitment overfishing in F! esculentus increases with increasing latitude.

Reproductive Pattern, Size at First Maturity and Stock-Recruitment Relationships of the Argentine Stiletto Shrimp (Artemesia Longinaris, Decapoda: Penaeidae) in Southern Brazil

“…Besides the influence on the period of the reproductive cicle, temperature also plays an important role on size at first maturity, in such a way that populations distributed in higher latitudes have later gonadal development and therefore reach larger LM (Courtney & Massel 1997). Comparison of mean length at first maturity of population inhabiting Southern Brazil (16.76mm) to investigations performed in northern and southern limits of distribution confirms this pattern.…”

Reproductive biology of the prawn Melicertus kerathurus (Decapoda: Penaeidae) in Thermaikos Gulf (N. Aegean Sea)

“…It is known that in closed thelycum species, the plot of the percentage insemination in each size class results in a more or less sigmoidal relationship, e.g., P. esculentus, P. semisulcatus (Crocos 1987a, b), M. longistylus, M. latisulcatus (Courtney and Dredge 1988), F. merguiensis (Crocos and Kerr 1983). However, contrasting results are reported even for the same species, as sigmoidal curve is not presented in P. esculentus by Courtney and Masel (1997). Moreover, although insemination increases with size, a typical sigmoidal curve is not shown in .…”

“…Interannual and monthly variations in reproductive activity of many other penaeid species have been reported (e.g. Courtney and Masel 1997;Crocos and van der Velde 1995;Minagawa et al 2000;Montgomery et al 2007;Hossain and Ohtomi 2008).…”

“…Dall et al 1990;Staples 1991;Crocos and van der Velde 1995). The interannual, seasonal, spatial (latitudinal), and size variations in spawning patterns of several penaeids have been documented (e.g., Crocos and van der Velde 1995;Courtney and Masel 1997;Minagawa et al 2000; Aragón-Noriega and Alcántara-Razo 2005; Montgomery et al 2007). …”

Comparison of two methods to determine the maturity period in penaeid shrimps (Decapoda, Penaeidae)

“…This, however, should be considered a biased index of reproduction, which should be modified by an index that includes both abundance data and data on fecundity-at-size (García, 1985). Courtney & Masel (1997) proposed an egg production index, EPI, composed of fecundity-at-size data, and data on the proportions of mature females. They found that this new index is a more quantitative measure of egg production in a population at a particular sampling station or sampling time.…”