The reproductive cycle and size at sexual maturity of the commercial whelk Buccinum isaotakii in Funka Bay, southern Hokkaido, Japan, was examined using monthly samples of individuals collected from May 1999 until October 2000. Female and male sexual maturity was determined based on reproductive organ sizes and histological examination, and sex ratios did not differ from parity. There were parallel annual cycles in the size of the ovary and pallial oviduct, and an inverse cycle for the digestive gland. The testis and seminal vesicle showed inverse cycles. The peak in seminal vesicle size was at the same time as the peak in ovary and pallial oviduct. The size of the male digestive gland exhibited no evident cycle. Males were mature from May to October 1999 and from April to October 2000, and spent individuals first appeared in September 1999 and then decreased in numbers until June 2000. Sperm content and epithelium in seminal vesicle indicated that the copulating period started in March and lasted until August 2000. Ovarian maturation and oogenesis occurred from October 1999 onwards and peaked in January 2000, with egg laying occurring from May until September. An increase in temperature coincided with the advancement of spermatogenesis and the egg laying while the transfer of the sperm from the testis to the seminal vesicle in males and the maturation of ovaries in females coincided with a decrease in temperature.

Only one specimen of Architeuthis dux was previously reported from the southern Indian Ocean. The present work adds ten new records of giant squid in the area. Two remains of fresh specimens have been collected from La Réunion Island (21°S) and Amsterdam Island (38°S) in tropical and subtropical waters, respectively. Eight other squid were identified from beaks found in stomach contents of sleeper sharks caught in Kerguelen waters (47 to 48°S) located in the southern Polar Frontal Zone. These new data together with published and unpublished information on the food of seabirds and marine mammals indicate that giant squid have a wide distribution throughout the southern Indian Ocean.

Age, growth and maturation of the temperate ‘mini-maximalist’ Idiosepius notoides from Tasmania is described and compared with those of its tropical congener Idiosepius pygmaeus. Using statolith increment analysis, growth of I. notoides was best described by a power curve with a maximum age of 115 days recorded. Males have a shorter lifespan than females, however growth rates were similar between the sexes. Idiosepius notoides grows to a larger size than its tropical counterpart. Onset of maturity in I. notoides occurred at an age of approximately 68 days for males and 88 days for females compared to 45–60 days for I. pygmaeus. Size at onset of sexual maturity was analogous between the two species, with males mature at approximately 6·5 mm mantle length (ML) and females at 14·0 mm ML. Idiosepius notoides, like I. pygmaeus, is a small short-lived sepioid with significant gender dimorphism and the capacity to spawn multiple times throughout its short life. This research supports the concept of similar cephalopod species living longer and growing larger in cooler environments.

Feeding and vertical distribution of pelagic chaetognaths were studied at coastal and open-sea stations in the northern part of the South Adriatic Pit during five cruises from April 1993 to February 1995. Chaetognaths were more numerous in the upper 100 m, decreased conspicuously with depth, and were captured only rarely between 600 and 1000 m. Copepods were the main food for the most abundant species in all layers. Cannibalism was evident in all species. Feeding on fertilized chaetognath eggs by Pseudosagitta lyra and Mesosagitta decipiens is reported for the first time. The food containing ratio (FCR) and number of prey items per chaetognath (NPC) of Flaccisagitta enflata were highest during the reproductive period. Higher FCRs and NPCs for M. decipiens and P. lyra were noted below 100 m, where the contribution of older specimens increased with depth and the abundance of copepods decreased.

The presence of angiotensin I-converting enzyme-like activity (ACELA) was investigated in whole body homogenates of Branchiostoma lanceolatum using a highly sensitive fluorimetric assay. The measured enzyme activity was inhibited by the two angiotensin converting enzyme inhibitors, captopril and enalapril, suggesting a biochemical pathway that could generate the angiotensins observed in the central nervous system of amphioxus.

This study investigates the catch components of a commercially used demersal trawl cod end in Izmir Bay, and reveals some of the morphological characteristics of nine commercial fish species; red mullet (Mullus barbatus), hake (Merluccius merluccius), whiting (Merlangius merlangus euxinus), poor cod (Trisopterus minutus capelanus), tub gurnard (Trigla lucerna), common pandora (Pagellus erythrinus), axillary sea bream (Pagellus acarne), picarel (Spicara smaris) and annular sea bream (Diplodus annularis) in relation to mesh size and shapes. Furthermore selectivity of 40-mm polyethylene netting cod end for red mullet, hake, common pandora, axillary sea bream, picarel and annular sea bream is presented. The results are discussed in a way to understand the probable effects of fish body shape on mesh selectivity.

Fifteen individuals of four marine fish species (Torpedo marmorata, Raja clavata, Scorpaena porcus and Scorpaena scrofa) caught in the Dardanelles, Turkey, were examined for the leech Pontobdella muricata and Trachelobdella lubrica; 18 P. muricata and 23 T. lubrica were found on gills, at the base of the fins, and abdomen on 14 of the 15 fish.

The sound characteristics and the sound producing system in silver sweeper, Pempheris schwenkii, are described. The main frequency component of the emitted sounds was 100–300 Hz, the mean duration of the sounds being 56 ms. The sounds were produced by paired extrinsic sonic muscles vibrating the swimbladder. The sonic muscles originated on the pterotic bones and extended to the anterodorsal surface of the swimbladder, and were innervated by two branches of the occipital nerves. Moreover significant sexual dimorphism of the sonic muscles was observed, those in males being three times as large as in females.

The olfactory organs in juvenile Dascyllus aruanus and Amphiprion ocellaris, studied by scanning and transmission electron microscopy (SEM and TEM), consisted of two bilaterally radial rosettes per specimen, fan-shaped, located medio-ventrally, one in each of two olfactory chambers. In D. aruanus the rosette comprises six lamellae, three on each side of a midline raphe; in A. ocellaris 12 lamellae, six on each side. In both species, the sensory regions in the lamellae are continuous, except for the margin of the lamellae, and richly covered with stereocilia. Areas with juvenile bipolar receptor cells were observed in both species. Two dissimilar types of olfactory receptor cells in the sensory epithelium: ciliated and microvillous were observed.

Histological analysis was used to describe and analyse the process of ovarian atresia in sardine (Sardina pilchardus sardina) from the central Aegean Sea (eastern Mediterranean). The spawning potential of females in relation to intensity of atresia was evaluated and the rate that the ovary passed from the active to inactive condition was followed in fish collected over an annual cycle. Early postspawning females, defined as those with 100% alpha-atretic oocytes, occurred throughout the spawning period; they had lower gonosomatic and hepatosomatic index, but similar total length compared to reproductively active females.

The reproductive biology of the tarwhine Rhabdosargus sarba has been studied in three very different environments in Western Australia, namely the lower reaches of the Swan River Estuary and marine waters at the same latitude, i.e. ≈32°S, and a large subtropical marine embayment (Shark Bay) approximately 800 km further north. A macroscopic and histological examination of the gonads demonstrated that R. sarba is typically a rudimentary hermaphrodite in Western Australian waters, i.e. the juveniles develop into either a male or female in which the ovarian and testicular zones of the gonads, respectively, are macroscopically undetectable. This contrasts with the situation in the waters off Hong Kong and South Africa where R. sarba is reported to be a protandrous hermaphrodite. Although R. sarba spawns between mid-late winter and late spring in each water body, the onset of spawning in the estuary is delayed until salinities have risen well above their winter minima. Although males and females attain sexual maturity at very similar lengths in the Swan River Estuary and Shark Bay, i.e. each L50 for first maturity lies between 170 and 177 mm total length (TL), they typically reach maturity at an earlier age in the former environment, i.e. 2 vs 3 years old. During the spawning period, only 25 and 12% of the males and females, respectively, that were caught between 180 and 260 mm TL in nearshore marine waters were mature, whereas 94 and 92% of the males and females, respectively, that were collected in this length-range over reefs, were mature. This indicates that R. sarba tends to move offshore when it has become ‘physiologically’ ready to mature. The L50s at first maturity indicate that the minimum legal length in Western Australia (230 mm TL) is appropriate for managing this species.

Trophic positions (TP) were estimated for the blue shark (Prionace glauca), shortfin mako (Isurus oxyrinchus), thresher shark (Alopias vulpinus), and basking shark (Cetorhinus maximus) using stable isotope ratios of carbon (δ13C) and nitrogen (δ15N). The basking shark had the lowest TP (3·1) and δ15N value (10·4‰), whereas the thresher shark had the highest values (4·5, 15·2‰). Mako sharks showed considerable variation in TP and isotopic values, possibly due to foraging from both inshore and offshore waters. Thresher sharks were significantly more enriched in δ15N than blue sharks and mako sharks, suggesting a different prey base. The δ13C values of thresher sharks and mako sharks varied significantly, but neither was significantly different from that of blue sharks. No statistical differences were found between our TP estimations and those derived from published stomach contents analyses, indicating that stable isotope data may be used to estimate the trophic status of sharks.

The first records of thorny skate eggs in stomachs of sperm whales are described. Predation on elasmobranch eggs, especially by marine mammals, is reviewed.

From June 1995 to August 2002 we assessed green turtle (Chelonia mydas) population structure and survival, and identified human impacts at Bahía de los Angeles, a large bay that was once the site of the greatest sea turtle harvest rates in the Gulf of California, Mexico. Turtles were captured live with entanglement nets and mortality was quantified through stranding surveys and flipper tag recoveries. A total of 14,820 netting hours (617·5 d) resulted in 255 captures of 200 green turtles. Straight-carapace length and mass ranged from 46·0–100·0 cm (mean=74·3±0·7 cm) and 14·5–145·0 kg (mean=61·5±1·7 kg), respectively. The size–frequency distribution remained stable during all years and among all capture locations. Anthropogenic-derived injuries ranging from missing flippers to boat propeller scars were present in 4% of captured turtles. Remains of 18 turtles were found at dumpsites, nine stranded turtles were encountered in the study area, and flipper tags from seven turtles were recovered. Survival was estimated at 0·58 for juveniles and 0·97 for adults using a joint live-recapture and dead-recovery model (Burnham model). Low survival among juveniles, declining annual catch per unit effort, and the presence of butchered carcasses indicated human activities continue to impact green turtles at this foraging area.

A towed trawl simulator sledge (TTSS2) for collecting quantitatively small macrobenthic animals disturbed by the passage of otter trawl groundrope typical of the local fishery is described and illustrated. The TTSS2 was towed from a surface vessel at a speed within the range of commercial trawls, incorporating three sampling nets that open and close by means of an electro-mechanical system. An odometer in contact with the seabed provided a continuous record of the trawled ground. The degree of efficiency of the TTSS2—by means of the attached groundrope that stirs up the surface of the bottom ahead of the nets—was tested in the northern continental shelf of Crete (eastern Mediterranean). Additional trials with a much heavier groundrope were also performed. Analysis and comparison of TTSS2 samples with endobenthic, hyperbenthic and planktonic samples collected by means of conventional sampling gears indicate the presence of a well-defined and distinct fauna in the plume of resuspended sediment behind the groundrope.