Marine traffic has both short- and long-term effects on cetacean behaviour, yet fishing vessels present a unique situation as they disturb cetaceans whilst potentially offering alternative foraging opportunities. The Istanbul Strait is a key area for the study of anthropogenic disturbance on cetaceans due to heavy human pressure in a narrow space where at least three cetacean species are regularly encountered. The present study investigated changes in behaviour of bottlenose dolphins, common dolphins and harbour porpoises in relation to the presence of purse seiners using Markov chains analysis. The results revealed increased foraging in bottlenose and common dolphins' behavioural budgets and a decrease in the time spent foraging by harbour porpoises. Moreover, a loglinear model was used to analyse the effect of possible confounding variables on observed behaviours. The only variables found to be affecting behaviour were the previous recorded behaviour, seiner presence and marine traffic density. Consequently, the presence of purse seine vessels leads bottlenose and common dolphins to change their behaviour and are related with a decrease of energy intake in porpoises. The results of this study reveal that there is an effect of purse seine vessel presence on the cetaceans found in the Istanbul Strait with potentially significant impacts on their behaviour, therefore we suggest more research is needed in the area to identify the long-term impacts of these observed behavioural changes.

Within the English Channel, the common cuttlefish Sepia officinalis is a semelparous species for which a 2-year life cycle was exclusively described in the 1980s. In the 1990s, new research indicated that whilst a 2-year life cycle was still evident for females and the large majority of males, a small proportion of males were actually maturing at only 1 year of age. Since 1980, the interest of French and UK fishers for this resource has increased and it is nowadays one of the most important demersal species of the area and is considered to be fully exploited. From the start of the 20th century, fishing effort and sea surface temperatures have increased in the English Channel and have probably impacted the life history traits of S. officinalis. A 2-year sampling programme was undertaken at French landing sites of the English Channel during the reproduction season in 2010 and 2011 to estimate if the proportion of 1-year-old mature animals has changed. Age determination was carried out by coupling polymodal decomposition and lipofuscin measurement. Size-at-maturity for each year and each sex was estimated by fitting a binomial error GLM. Results highlight that a variable percentage of males and females belonging to the first cohort are mature and that size-at-maturity was lower than that observed in the 1990s. Finally, different parameters, such as temperature and fishing pressure are explored to discuss changes in life history traits suggesting that cuttlefish could be an indicator of the temperature regime shift in the English Channel.

Review of the available literature and the results of the present study revealed that 17 specimens of Isurus oxyrinchus were caught between 1950 and 2013. Nine (52.9%) of these verified 17 catches were recorded after 2000. Catches of I. oxyrinchus off Turkey's coast include specimens ranging from new-borns (65 cm total length) to huge adults (585 cm total length). A new-born female caught off the coast of Foça on 19 May 2015 represents the smallest free-swimming specimen of I. oxyrinchus ever recorded in Turkish waters. The occurrence of a new-born shortfin mako shark off Foça's coast provides new evidence to support the possibility of a mating region of lamniform sharks, including I. oxyrinchus, in the northern Aegean Sea. The seasonal occurrence of both young and adult shortfin mako sharks off Turkey's Aegean and Mediterranean coasts should be monitored to clarify whether the shortfin mako shark is a resident or a vagrant species along the aforementioned coastline.

Field surveys and literature review revealed the capture of 50 bluntnose sixgill sharks from the Sea of Marmara. Total lengths of the observed specimens ranged from 1.2–6 m, and weighed between 10 and 1000 kg. Nine specimens were males, 23 were females and 18 were of unknown sex. Regarding the bathymetric distribution of the captured bluntnose sixgill sharks, majority of the specimens (78%) were recorded in slope and shelf waters of the eastern and northern Sea of Marmara. Fishing presents the only known proximate threat to bluntnose sixgill shark populations in Marmaric waters. Inclusion of Hexanchus griseus in the endangered marine fish list of the Turkish Fisheries Act, would be the first step before subjecting H. griseus to 100% protection.

The present paper analyzes data collected between 2001 and 2002 on 81 reef fish species targeted by fishers at 5 sites in the Kingdom of Tonga (South Pacific). We first ranked the sites with respect to fishing pressure using two independent methods: (i) Tongan demography and reef surfaces available for fishing, and (ii) the differential effects of fishing on the whole set of 81 species grouped by their life history traits (LHT). We then focused on Parrotfish (Scaridae), which are heavily targeted in coral reef fisheries. We used the identified gradient of fishing pressure to study the effect of fishing on the community structure and test the hypothesis of “shifting dominance” amongst the 20 Scarid species present in the surveys. In addition to the classical effect of decreasing fish size in a family strongly targeted by fishers, the shifting dominance phenomenon includes a decrease in the abundance of the large-bodied and highly targeted species, favouring their replacement by smaller-bodied species from the same family, which are less impacted by fishing. In a context of interspecific competition amongst Scarids, the stress of fishing appears as a factor favouring the replacement of species with large maximum size, and LHT promoting low resilience, by smaller species with the opposite attributes. The discussion focuses on the various processes that can explain the shifting dominance phenomenon. The total density of resilient species, which increased along the gradient of increasing fishing pressure, can be used as an indicator of the over-exploitation of fish communities for reef fisheries management.

Marine reserves are widely considered to potentially benefit reef fisheries through emigration, yet the empirical basis for predicting the extent of this for small reserves is weak. The effects of fishing pressure and habitat on biomass and catch per unit effort (CPUE) of three species of exploited reef fish were studied at South Caicos, Turks and Caicos Islands. Distribution and abundance of hogfish (Lachnolaimus maximus) and white margate (Haemulon album) were inversely correlated with cover of fleshy macroalgae. Nassau grouper (Epinephelus striatus) were positively associated with vertical relief, but were unaffected by algal cover. Mean size, density, and biomass of hogfish were higher in a small (4 km2) marine reserve than on fished reefs, as was biomass of white margate. CPUE of hogfish was inversely related to distance from the centre of the reserve, suggesting that spillover of this species from the reserve to adjacent reefs may enhance local yields, possibly providing economic incentives for fishers to comply with reserve regulations. Fishing pressure, however, had no apparent effect on Nassau grouper. Larger fishes and those that migrate to spawn, such as economically valuable Nassau grouper, may move over too large a range to be effectively protected by small marine reserves. Small reserves may not protect all fish, but they can increase the biomass of smaller or more sedentary reef fishes and may be a useful tool for the conservation or management of species such as hogfish. Other policy options, such as seasonal spawning closures or total allowable catches, need to be considered for larger, more mobile fishes in the Turks and Caicos Islands.