No abstract

The food habits of the silver pomfret, Pampus argenteus (Euphrasen 1788), in Kuwait waters were investigated by examining the stomach contents of 738 specimens collected from May 1996 to April 1997. Their diet consisted of a broad spectrum of food types, but Crustacea were dominant, with copepods and their eggs constituting 39 % other non‐copepod Crustacea constituted 16 %. The next major food group was Bacillariophyta (21 %), followed by Mollusca (11 %), fish scales (10 %) and, finally, fish eggs and larvae (3 %). In summer the species fed on a wider variety of food items than in winter. Copepods, other non‐copepod crustaceans, and molluscs tended to occur in the stomachs in higher frequencies with an increase in P. argenteus size (up to 18.5–20.4 cm), while the bacillariophytes tended to increase in stomachs at fish sizes between 22.5–24.5 cm. Analysis of monthly variations in stomach fullness indicated that feeding intensity fluctuated throughout the year, with a low during August and September, corresponding to the spawning period.

The reproductive activities of the silver pomfret\ Pampus arg! enteus "Euphrasen#\ in Kuwait waters were investigated from March 0885 to February 0887[ Observations on the seasonal distribution of maturity stages and variations in seasonal~uc! tuations in the gonadosomatic index "GSI# con_rmed recent _ndings 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 Septem! ber[ The recruitment pattern con_rmed the one breeding season[ There are two spawning peaks\ the _rst in May and the second in August[ Variations in GSI relative to _sh length indicated that females and males are most fecund at about 13[4Ð15[3 cm and 19[4Ð11[3 cm length classes\ respectively[ The males mature earlier than females\ at a minimum size of 01[4Ð03[3 cm\ while the females mature at 19[4Ð11[3 cm[ The oocyte diameterÐfre! quency distribution suggests a serial rhythm of spawning[ Fec! undity ranged from 17 854 to 344 550 and correlated positively with] "a# standard length "P ³ 9[995#^"b# ovary weight "P ³ 9[990#^and "c# body weight "P ³ 9[990#\ and negatively with egg size "P ³ 9[992#[

Effects of location, diel period, tidal condition and water clanty on the size and distribution of the shallow water fish assemblage of the non-estuarine Kuwait Bay, were investigated using a beach seine and a small research trawl during spring and summer 1989. Total numbers, biomass and numbers of species differed markedly between Doha, a sandy shore environment, and Kazmah, an extensive intertidal mud flat. When fish were present in large numbers there was a marked die1 effect at both locat~ons with many more fish captured during the mght. Tidal effects were influenced by turbidity and the age structure of the assemblage. In clear water during spring, very young Liza carinata from the seine catches formed shoals at the edge of the rising tide both day and night, while fish 2 mo older formed shoals only on daytime r~s i n g tides. At Kazmah during spnng, h~g h turbidity obscured any tidal effects in the seine catches. In shghtly deeper water, sampled by trawl during spring, Leioynathus decorus showed an asymmetrical hdal migration In summer, beach seine catches were much higher on the rising tide. Summer trawl catches did not show a consistent tidal effect

With 7 figures in the text)The biology of the very early stages in the upstream migration of the River lamprey has been studied using samples taken from the cooling water intake screens of the Oldbury Power Station in the Severn Estuary. Examination of the numbers of lampreys caught at different times indicate that an increase in freshwater discharge is the predominant environmental factor responsible for initiating the movement from the sea into the estuary, although temperature may also be a contributory factor. The migrants could be separated on the basis of size into typical and praecox forms whose mean lengths during peak abundance were approximately 300 and 240 mm respectively, the corresponding weights being about 53 and 22 g respectively. The typical forms were occasionally found in the estuary as early as July and as late as April, with peak abundance generally being reached in November, whereas the praecox forms were present mainly between January and March. The ratio of typical to praecox forms over the four years of sampling was estimated as 3.3 : 1. In both size categories, the gonadosomic and hepatosomic ratio was greater in females than males. Evidence was also found in the typical forms for a correlation between high numbers and an increased proportion of males. Measurement of a number of different characters, including lengths, weights and condition factors, as well as gonadosomic, hepatosomic and gut ratios, suggest that, although the typical forms enter the estuary over a long period of time, the onset of the changes leading to sexual maturity are more synchronous. A small number of the later typical migrants, however, exhibited different characteristics to those of the majority of the animals comprising this size category. Measurements made on typical animals from Oldbury in November indicate that they can regulate their plasma ions in salinities as high as 70% of full strength sea water.