History and current checklist of Kuwait's ichthyofauna

Summary

Silver pomfret, Pampus argenteus, were collected by fishing with drift gillnets on one spawning ground in Kuwait waters during 1998–2000. Fish size frequency, sex ratio, maturation cycle, spawning frequency, fecundity and egg weight were assessed. The length–weight relationship differed between sexes whereby females were significantly bigger than males. Spawning started in mid-May and continued until early October. During this time the water temperature ranged from 26.0 to 32.8°C, salinity was ≅ 39.0‰ and water depth ranged between 5 and 12 m. Large females spawned earlier than young spawners and the overall percentage of males during the spawning period was 70.3%. Spawning occurred after 13.00 h, with peak spawning between 15.00 and 18.00 hours during outgoing tide. Mean daily spawning frequency amounted to 63.2%. Spawning activity was found to be associated with the lunar cycle and spawnings were concentrated during the first and third quarters of the moon period, indicating a semilunar reproduction cycle. It was concluded that a female would spawn at least six times during the season. No change was observed in relative fecundity during the peak spawning season (June–August). Average relative batch fecundity was 176.3 eggs g−1 somatic weight (SW), corresponding to a relative total fecundity of 1058 eggs g−1 SW, which is 1.5 times higher than estimates obtained from counting the standing stock of oocytes. Bigger fish produced heavier eggs and the egg weight decreased as the spawning season progressed. Based on gonadal cycles, oocyte size frequency distribution and total fecundity, we concluded that silver pomfret is a multiple batch spawner with indeterminate fecundity.

Spawning frequency, fecundity, egg weight and spawning type of silver pomfret, Pampus argenteus (Euphrasen) (Stromateidae), in Kuwait waters

Summary
The reproductive activities of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters were investigated from March 1996 to February 1998. Observations on the seasonal distribution of maturity stages and variations in seasonal fluctuations in the gonadosomatic index (GSI) confirmed recent findings that the spawning period begins in May. The species has a prolonged spawning period in the females extending from May to August, whereas the males mature in April and ripe specimens were encountered in monthly samples until September. The recruitment pattern confirmed the one breeding season. There are two spawning peaks, the first in May and the second in August. Variations in GSI relative to fish length indicated that females and males are most fecund at about 24.5–26.4 cm and 20.5–22.4 cm length classes, respectively. The males mature earlier than females, at a minimum size of 12.5–14.4 cm, while the females mature at 20.5–22.4 cm. The oocyte diameter-frequency distribution suggests a serial rhythm of spawning. Fecundity ranged from 28 965 to 455 661 and correlated positively with: (a) standard length (P < 0.006); (b) ovary weight (P < 0.001); and (c) body weight (P < 0.001), and negatively with egg size (P < 0.003).

Reproductive biology of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters

The reproductive activities of the grey mullet, Liza klunzingeri (Day, 1888) in Kuwaiti waters were inves- tigated from March 1998 to February 1999. Contrary to existing view that grey mullet in Kuwaiti waters spawn from December to February, evidence is presented that indicates a prolonged spawning period, beginning from November and ending in March. The maturation pattern is divided into seven stages in both male and female. Variations in GSI relative to fish length indicate that males reach maximum reproductive capacity at between 13.1-17.0 cm, and females at 14.1- 18.0 cm. During the fishing campaign, females outnumbered males in the samples in a ratio of 2:1. The oocyte diameter- frequency distribution suggests a synchronous oocyte development with a single, total spawning. Fecundity ranged from 88,896-185,929 eggs. The species inhabits unstable habitats (estuaries and coastal areas) which, in the Kuwait Bay, are threatened. This, coupled with the fact that they generally grow to relatively small size, attain the most fecund status also at a small size, and have high fecundity, suggest that the species is r-selected, as opposed to the so-called K-selected species which inhabit stable environments, grow to relatively large sizes, with delayed reproduction, and low fecundity. RESUME. - Le cycle de reproduction mâle et femelle du mulet gris, Liza klunzingeri (Day, 1888) dans les eaux koweiti- ennes du golfe Arabique. La reproduction du mulet gris, Liza klunzingeri (Day, 1888) a ete etudiee dans les eaux du Koweit de mars 1998 a fevrier 1999. Contrairement aux informations actuelles, selon lesquelles la reproduction aurait lieu de decembre a fevrier, il s'avere que la saison de ponte est beaucoup plus longue : de novembre a fin mars. La maturation peut etre decrite par 7 stades chez les mâles comme chez les femelles. Les variations du RGS avec la longueur indiquent que les mâles atteignent une capacite reproductrice maximale pour une taille comprise entre 13,1 et 17,0 cm et les femelles une fecondite maximale entre 17 et 18 cm. Durant la campagne de peche, le sexe ratio observe est 2 femelles/mâle. Les distributions de frequence du diametre ovocytaire suggerent un developpement synchrone des ovocytes avec une ponte unique par saison de repro- duction. La fecondite est comprise entre 88 896 et 185 929 œufs. Au Koweit, l'espece colonise de facon instable divers habitats (estuaires et zones cotieres) qui sont menaces par les pollutions. Cette observation, couplee au fait que les tailles maximales sont relativement faibles, que la maturite sexuelle est atteinte a une petite taille et que la fecondite est elevee, suggere que la demographie de l'espece serait de type r selection plutot que de type K, pour laquelle les especes ont une taille relativement elevee, une reproduction tardive et une faible fecondite.

Reproductive cycle in the male and female grey mullet, Liza klunzingeri in the Kuwaiti waters of the Arabian Gulf

Summary

The population dynamics of the black pomfret, Parastromateus niger, sampled from commercial gill-net catches from Kuwaiti waters of the Arabian Gulf, were investigated from October 2003 to September 2005. Length-based stock assessment using the FiSAT software package showed an asymptotic length of 65 cm TL and growth curvature of 0.34 year−1. Raw data as well as that corrected for probability of capture indicated a recruitment from February to September. The total mortality coefficient was estimated to be 1.20, a natural mortality of 0.68 and fishing mortality of 0.52. The selectivity model based on the running average showed that 25% of 14.0 cm TL fish, 50% of specimens reaching 16.3 cm TL, and 75% of all specimens of 20.2 cm TL encountering the gear were retained. Relative yield-per-recruit analyses revealed a current exploitation rate of 0.43; this is below the maximum sustainable yield index, indicating for sustainable fishery of P. niger that the exploitation rate could be increased to 0.6, provided size of the fish at first capture, i.e. the legal size, is also increased to 32.5 cm TL. These results suggest that P. niger stocks in Kuwaiti waters, contrary to existing views, are moderately exploited. This conclusion, however, is critically dependent on the estimate of natural mortality, which requires further confirmation.

Population dynamics of Parastromateus niger in Kuwaiti waters as assessed using length–frequency analysis

The spawning periodicity of silver pomfret, Pampus argenteus (Euphrasen), was investigated against a background of conflicting evidence on the onset of spawning in this species. Contrary to the existing view that silver pomfret in Kuwait waters begin to spawn in March–April, evidence is presented that indicates a delay in spawning until May. Only an insignificant level of spawning takes place in April which, from the management point of view, may be ignored. The species has a prolonged spawning period extending from May to August in females, although the males mature in April and ripe specimens are encountered in monthly samples until September. There are two spawning peaks, the first one in May and the second in August.

F. Abou-Seedo

Papers

Reproductive biology of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters

The onset of spawning in the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters and its implications for management