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In this study, four species of penaeid shrimp from Pakistan's inshore waters were studied. These were Penaeus penicillatus (Alcock), Penaeus merguiensis (de Man), Metapenaeus affinis (Milne Edwards) and Parapenaeopsis stylifera (Milne Edwards). During maturation, shrimp ovaries pass through a series of colour changes. The various colours observed in the ovaries of the four species of penaeid shrimps were translucent, white, cream, yellow, green-yellow, green-white, light green and dark green. The different type of oocytes observed in histological sections of the penaeid ovaries are as follows: chromatin nucleolar oocytes, perinucleolar oocytes, yolkless oocytes, yolky oocytes and oocytes with cortical bodies. The ovarian developmental stages recognized in these shrimps are: undeveloped, developing, nearly ripe, fully ripe, resorbing and resorbing/ developing. The ovarian developmental stages were similar in all the four species with the exception of the fully ripe stage. In the fully ripe stage of P. penicillatus and P. merguiensis, the cortical bodies were present at the periphery in two shapes; spherical as well as rod-like. On the other hand, in the fully ripe stage of M. affinis and P. stylifera, the cortical bodies were present only at the periphery and were only spherical. A relationship between colour of ovaries and histological stages of ovarian development was established. A female shrimp with a dark-green ovary is an indication of the readyto-spawn condition. In P. merguiensis and Penaeus penicillatus, respectively, 100% and 88.1% females with dark-green ovaries had oocytes with cortical bodies, whereas in M. affinis and P. stylifera, respectively, 50% and 28.6% females with dark-green ovaries had oocytes with cortical bodies.

In Pakistan, although the sea cucumber fishery has not yet been developed,Holothuria arenicolais abundant on its coast. Nineteen months of sampling was carried out to study the population structure, allometric relationships and reproductive status ofH. arenicolastocks in Manora and Buleji rocky shores. All measured biometric characters showed significant temporal variations and width/length, weight/length, gutted weight/length and gutted weight/weight relationships followed negative allometry, indicating a change in body shape as the animal grows. Length-frequency distribution analysis was bimodal in both summer and autumn consisting of small-sized and medium-sized individuals while in winter and spring three modes were found at Manora. At Buleji, the population was unimodal in all seasons consisting of small-sized individuals. Sex inH. arenicolacannot be determined externally but can be identified on examination of gonad colour which is orange-like in females and creamy yellow in males. The sex was further confirmed on histological examination and maturation was divided into five stages, i.e. undetermined, early developing, late developing, mature and partially spawned. The sex ratio inH. arenicolawas approximately 1:1 and increase in gonad index was observed during spring and early summer, followed by a decrease in GI in autumn and winter, which showed the spawning followed by resting phase. The GI showed a significant negative correlation with salinity and non-significant correlation with temperature. There is a need to undertake more biological/ecological studies onH. arenicolain order to take effective measures for its management.

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Endocrine mediated "imposex" phenomenon was investigated and recorded in the muricoid gastropod species Thais carinifera during the two decades from 1993 to 2012 at three (3) sites out of six (6) localities investigated along the Sindh and Balochistan coast, Pakistan. The VDS stages 1 to 4 were apparent in Thais carinifera. The intensity of imposex has remained comparatively low in the populations of harbours in close proximity to port Mohammad Bin-Qasim, namely; Old Korangi Fish Harbour (OKFH) and New Korangi Fish Harbour (NKFH) where shipping activities are sporadic as compared to those in Manora Channel and the adjoining Karachi Port area where intensive shipping activity is rather frequent. Target species found to be good bioindicators have shown a marked decrease over the prolonged study period. Investigations show that this decrease is solely due to globally imposed effective bans on tributyltin (TBT) based antifouling paints over the past decade. AbstrActDescriptors: Imposex, Gastropod, Biomonitoring, Endocrine Disruption, Karachi Coast. O fenômeno hormonal "imposex" foi investigado e relatado para o gastrópode muricídeo Thais carinifera durante duas décadas, de 1993 a 2012, em três das seis localidades investigadas ao longo da costa de Sindh and Balochistão, Paquistão. Os estágios VDS 1 a 4 foram aparentes na espécie. A intensidade do imposex permaneceu comparativamente baixa nas populações dos portos próximos do porto de Mohammad Bin-Qasim, especificamente em Old Korangi Fish Harbour (OKFH) e New Korangi Fish Harbour (NKFH), onde as atividades portuárias são esporádicas quando comparadas às de Manora Channel e à área adjacente do Porto de Karachi, onde a atividade portuária é mais intensa. A espécie alvo mostrou-se um bom bioindicador por ter apresentado decréscimo acentuado ao longo do extenso período de estudo. As investigações mostraram que esse decréscimo é apenas devido ao efetivo banimento globalmente imposto da tributiltina (TBT) como base de tintas anti-incrustantes ocorrido na década passada. resumoDescritores: Imposex, Gastrópodes, Biomonitoramento, Perturbações Endócrinas, Costa de Karachi.

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Annual reproductive cycle and spawning ecology of Kelee shad, Hilsa kelee were studied. The sex ratios did not exhibit as 1 : 1; whereas 69.19% were females. On the basis of histological examination, the maturity of female gonads of H. kelee was categorized in eight developmental stages: immature, developing, fully developed, hydrated, running ripe, partially spent, spent and post spawning. Whereas males of this spe cies were categorized in five developmental stages: immature, developing, ripe, partially spent and spent. This fish is repeatedly spawner and spawns twice per year: in April to June and August to October. The values of exponent b in the length weight regressions (W = al b ) slightly varied in males b = 3.133, R 2 = 0.96 and P < 0.01 and females b = 3.143, R 2 = 0.95 and P < 0.001. The linear regressions of length weight relationships were significant for both males and females.