An experiment was carried out to estimate the rate of indirect fishing mortality on juvenile Spisula solida due to the exposure time on deck. Samples were collected using a dredge from a site off Vilamoura, south coast of Portugal, during July 1994. Length of deck exposure is directly related to mortality of juveniles. It was estimated a fishing mortality rate of 0.00335 per min, due to length of exposure.

An analysis of species composition of the zooplankton, macrobenthos (two stations) and demersal fish from Northumberland (north-west North Sea) are reported. The four time-series show synchronous changes in species composition. While some of these changes coincide with changes in climateological variables, others do not. The degree of synchrony implies that either all the time-series are responding to a single set of extraneous forcing factors, or that food chain links, rapidly translate the signal through all ecosystem components.

Specimens of Euchaeta norvegica and Euchaeta hebes (Crustacea: Copepoda) were collected west of the Isle of Man, Irish Sea, between February and April 1993. There are no previous records of these species in the plankton of the Irish Sea. It is thought that they were carried into the central southern Irish Sea by incursions of water through the St George's and North Channels.

Supralittoral rockpools form an extreme environment due to severe fluctuations in salinity, temperature and oxygen concentration. The only seaweed species in supralittoral rockpools around Great Cumbrae, Firth of Clyde was the green alga Enteromorpha intestinalis. Only two animal species were recorded permanently over a three year period in this environment; the orange harpacticoid copepod, Tigriopus brevicornis, and the chironomid larva, Halocladius fucicola. The present study demonstrates the role of the hollow thallus of E. intestinalis in the lifestyles of T. brevicornis (adults and nauplii) and H. fucicola. The thallus provides a moist refuge reducing desiccation when the rockpools completely dry out. Several hundred individuals of T. brevicornis have been observed in a single E. intestinalis thallus. This observation may explain how the species can successfully recolonize completely evaporated supralittoral rockpools after several weeks. The study also raises questions about the reliability of previous population estimates of Tigriopus spp. in light of this constantly overlooked refuge.

The effect of polarized light on the shade-seeking behaviour of the ophiuroid Ophioderma brevispinum was investigated at the Keys Marine Laboratory, Long Key, Florida, USA. Animals were collected and placed in a partially shaded arena. When the arena was illuminated with unpolarized light, the number of animals settling under the shaded portion of the arena was not significantly different from random (N=30, P>0.3). When the arena was illuminated with linearly polarized light, the number of animals settling in the shaded portion of the arena was approximately double what would be expected in a random distribution (N=30, P<0.001). The results are further evidence that O. brevispinum is sensitive to polarized light and are consistent with the hypothesis that polarized light may be used by the animals as an indicator of harmful levels of solar ultraviolet radiation.

Since 1995, research cruise catches of anchovy Engraulis encrasicolus (Pisces: Engraulidae) have increased in the Irish Sea. Their distribution shows distinct seasonality with anchovy being found in the deeper waters of the western Irish Sea in the spring and spreading out into the eastern Irish Sea by summer and autumn. Their length distributions show two modes at 7–11 cm and 13–16 cm.

Anonyx sarsi (Crustacea: Amphipoda) is a widely distributed scavenger and predator in shallow waters of northern seas. It was caught, often in large numbers, in baited traps in the intertidal in Iceland, especially during mid-winter. Although hitherto only sporadically recorded from the intertidal, the species is undoubtedly among the most important carrion feeders there, and probably an important predator as well.

Alepocephalus bairdii is a deep sea fish caught but discarded by semi-industrial fisheries from the north-east Atlantic Ocean. Reproductive features were investigated on 448 females of 29–93 cm standard length (SL) captured over 2 y (December 1995–December 1997) at 800–1280 m off the west coast of the British Isles. The first maturity of females was determined at L50=55 cm SL. A well-defined spawning period could not be determined in this species; a batch spawner characterized by an indeterminate annual fecundity. Absolute batch fecundity was estimated between 458 and 7049 oocytes per female 63–88 cm SL.

The stomach contents of 899 whiting, Merlangius merlangus (Pisces: Gadidae), from the central and southern North Sea, were analysed. Crustacea and fish comprised 90% on average by weight of the food observed. Crustacean prey sizes usually ranged from 0.2 to 0.6 g. The mean daily consumption of a common invertebrate prey, Crangon crangon, was estimated to be 0.1 g for a whiting weighing 150 g.

Size of ripe eggs and potential fecundity are described in the squid of the subfamilies Todaropsinae and Todarodinae (Oegopsida: Ommastrephidae)—Todaropsis eblanae from West Africa, Todarodes angolensis from Namibia, Todarodes sagittatus from north-west Africa and the Mediterranean Sea, Todarodes sp. from the south-east Pacific, Nototodarus hawaiiensis from the south-east Pacific and West Indian Ocean and Martialia hyadesi from the south-west Atlantic. Females of both subfamilies are characterized by a wide range of ripe egg size (0.7–2.4 mm) and low and medium values of potential fecundity (20,000–2,500,000).

A hitherto unreported association between the isaeid amphipod Photis longicaudata and the hexacorallian Cerianthus lloydii is described and illustrated from material collected near Millport, Clyde Sea area. By building their tubes around the outside rim of the anemones' tubes, this amphipod presumably gains proximity protection from predators.

Galathea intermedia is common, but cryptic, on Clyde maerl deposits where it lives in small groups of mixed sex and age, sharing shelters (typically dead Dosinia shells) to avoid predation. Its appearance is marked by six iridescent blue spots which may play an important role in intra- or interspecific interactions.

The duration of residence at identifiable refuges in separate territories was assessed over an 800-d period for the goldsinny, Ctenolabrus rupestris, a territorial labrid (Osteichthyes: Perciformes: Labridae), on the west coast of Scotland. Goldsinny (N=12; seven male, five female) were taken from, tagged and returned to, marked refuges using anaesthetics applied underwater. Over the whole study period two goldsinny (one male, one female) moved between adjoining territories, but most (eight out of the ten recaptured or observed) remained in the refuge in which they were released.

In 1993, a 100-y return-time flood brought about major hydrological changes in the Vaccarès Lagoon (Rhône Delta, France). Four years after the floods, Gobius niger had disappeared from the lagoon. Only the fall in salinity can explain this change. Reproductive traits in 1993 and 1994 were compared to determine the choices this species takes to improve its fitness in such unfavourable conditions. Evidence suggesting that G. niger is not a sedentary lagoon species is also discussed.

During the winter of 1996, a heavy storm crossed the coasts of the Azores. A comparison of wave-exposed and wave-sheltered samples of the intertidal planktonic developing periwinkle Littorina striata (Mollusca: Caenogastropoda), collected before and after this storm revealed: (1) an overall difference in relative and absolute aperture area between wave-exposed and wave-sheltered samples; and (2) depending on the technique used a storm (MANOVA/CDA/1994 vs 1996 nested ANOVA) or no storm (1992, 1993, 1994, 1996, nested ANOVA) effect was noted. Preference should be given to the latter analysis as it is more correct in the present context. Nesting of the factor ‘year’ in the factor ‘storm’, allows detection of the true storm effect, disentangling it from other year exposure interactions, while the inclusion of more than one pre-storm sample allows differentiation of storm effects from ‘normal’ temporal variation.

Research into the feeding habits of cetaceans has traditionally relied on examining samples taken from the digestive tracts of commercially caught or stranded and by-caught animals. This depends on the identification and measurement of hard parts such as fish otoliths. Otoliths are often partially digested in the stomach, making quantitative estimates of fish size from otolith size biased.

As a preliminary attempt to quantify the size reduction of otoliths found in the stomachs of small cetaceans, an in vitro digestion experiment was carried out. Otoliths of herring, whiting, poor cod and haddock were digested at 37°C, pH=3·6, and measured every 60 min.

Linear regressions relating otolith size to digestion time and original size generally provided an adequate description of the time course of size reduction. The parameter that changed most rapidly due to digestion was otolith thickness. Differences in digestion rates between species reflect the general robustness and shape of the otoliths.

A simulation using actual dietary data showed that the overall diet composition was not radically changed by accounting for otolith digestion, although the apparent contribution of herring increased as the assumed digestion time is increased, because herring otoliths were the most susceptible to digestion.

Laboratory based experiments, carried out on Littorina neglecta collected from the barnacle zone at Ravenscar, north-east England, showed that this marine prosobranch displays size assortative mating. Males prefer to mate with larger, more fecund females, but they do not necessarily choose the largest available. It is suggested that such size assortative mating may act as a barrier to reproduction between L. neglecta and L. saxatilis. No relationship was found between either male or female shell size and the length of copulation.

As part of my ongoing studies of the Callianassidae, Dr G. Poore of the Museum of Victoria, Australia, sent me four small specimens from Tasmania. These specimens, which include two ovigerous females, are closely allied to Callianassa lewtonae from the northern Great Barrier Reef, Queensland, Australia. They differ from that species because the merus of the chelipeds bears a triangular ventral lobe in the larger cheliped and a sharp ventral spine in the smaller cheliped; and the antennular peduncle is much longer than the antennal peduncle. Only Callianassa ceramica, C. arenosa, and C. australiensis have been previously recorded from Tasmanian waters.

Abbreviations used are: MV, Museum of Victoria, Australia; CL, carapace length; TL, whole length of the specimen from the tip of rostrum to the end of telson; A1, antennule; A2, antenna; P, pereiopod; Plp, pleopod.

The swimming and swarming behaviour of Tritodynamia horvathi (Brachyura: Pinnotheridae) has been considered to be a seasonal activity related to summer mating. However, little information has been available regarding other seasons of the year as the crabs have not been observed at the sea surface in the cool months from October until May. This is the first report of swimming behaviour observed during this low temperature season. The swimming individuals were observed in March 1991 in Yatsushiro Sound, Japan. Tritodynamia horvathi were observed swimming at a depth of 15 m, using their maxillipeds to feed. The crabs also swam in the aquarium and caught Artemia nauplii in the same manner. These findings suggest that their swimming behaviour is not a seasonal mating activity as previously believed, but a habitual behaviour associated with feeding.