Comparison of the population structure and life-history parameters of Diplodus capensis (Sparidae) in exploited and unexploited areas of southern Angola

Blacktail seabream Diplodus capensis were sampled from proximate (10 km apart) exploited and unexploited areas in southern Angola to compare their population structures and life-history parameters. Females dominated the larger size and older age classes in the unexploited area. In the exploited area the length and age frequency distributions were more equitable, but there was a lack of large and old individuals in this area due to the selective nature of fishing gear. Growth zone deposition rate was validated as being annual using mark-recapture of chemically injected (oxytetracycline) fish. In the unexploited area, females attained larger sizes and greater ages than males; however, growth and longevity were more equitable between the sexes in the exploited area. Length- and age-at-50% maturity were similar between the sexes in both areas. The sex ratio was heavily female-skewed (1:4.7) in the unexploited area but less so in the exploited area (1:2.2). Although the growth curves were significantly different for fish between areas, this was likely due to a reduction in longevity rather than a physiological change in growth. The length- and age-at-50% maturity was also similar between areas, indicating that this species either does not have the ability to respond to exploitation through physiological change in these life-history characteristics, or that the current level of exploitation is not high enough to elicit such a response. However, the female dominance in the smallest size class in the exploited area (compared to the unexploited area) indicated that a threshold may have been reached, and that this species responds to exploitation by increasing the relative number of fish that mature as females.     

Direct impacts of commercial and recreational fishing on spiny lobster,Panulirus interruptus,populations at Santa Catalina Island,California, United States

The California spiny or red rock lobster, Panulirus interruptus, is an ecologically and economically important species that has been exploited since the 1800s. No previous study in California has assessed the impacts of the recreational or commercial lobster harvest. Before the 2003–04 commercial and recreational lobster seasons, we conducted a fishery‐independent trap survey at Santa Catalina Island to document the impact of the lobster fisheries on the size structure, abundance, and sex ratios of mature P. interruptus (>65 mm carapace length (CL)). We concurrently sampled a predominantly commercially fished area, a recreationally fished area, and a 23‐year‐old invertebrate no‐take (INT) reserve. Relative to the INT reserve, legal‐size lobsters in the recreational area were similar in CL, but 31% less abundant. Legal‐size lobsters in the commercial area were 8% smaller and 70% less abundant than those in the INT reserve. The sex ratio of legal‐size lobsters, although near 50:50 in the recreational and INT reserve areas, was male‐dominated (67:33) in the commercial area. Differences in CPUE and mean CL of sub‐legal lobsters in the recreational and commercial areas suggest that factors in addition to harvesting pressure may affect these populations. Total biomass of mature lobsters in the recreational and commercial areas was 92% and 45%, respectively, of biomass in the INT reserve. Fecundity in the recreational and commercial areas was 83% and 42%, respectively, of fecundity in the INT reserve. This study provides preliminary data for future ecological studies and fisheries management evaluations.     

Marine reserve effects on population density and size structure of commonly and rarely exploited limpets in South Africa

Marine reserves are commonly used to conserve living resources, but their effectiveness where policing is difficult is unclear. We compared monthly population density and size structure data collected over 20 months for two rarely and two commonly exploited intertidal limpets inside and outside reserves in South Africa. Densities were greater inside reserves, but significantly so in very few months. Unexpectedly, no significant reserve effect was detected for the territorial Scutellastra longicosta, shown by surveys to be favoured by harvesters. Reserve effects for the rarely exploited S. granularis probably result from indirect effects of higher barnacle cover in reserves where trampling is reduced, while interviews indicated that Cellana capensis is not targeted but large individuals are sometimes misidentified and hence are harvested outside the reserve. There were few reserve effects on mean or mean maximum size. The results indicate a gradient of exploitation among species and sites. One non-reserve site was more heavily exploited than the other, while one reserve experienced more poaching than the other. The effectiveness of marine reserves thus differed between reserves and among species. Exploited limpets were generally larger and at higher densities in reserves, but these effects were rarely statistically significant, indicating that reserve effects are weak compared to natural variability, probably reflecting ineffective policing.     

Dynamics of water exchange and salt flux in the Macuse Estuary,central Mozambique,southern Africa

The Siberian subspecies of the red knot Calidris canutus canutus spends the non-breeding season largely in West Africa (Mauritania and Guinea Bissau), where approximately half a million occurred in the 1980s. It was a rarely seen in southern Africa in the early part of the 20th century, but there were about 12 500 in the 1970s and 1980s. The main sites were Langebaan Lagoon, Berg River Estuary, Olifants River Estuary (South Africa) and Walvis Bay Lagoon (Namibia). There was a decline in the number of red knots at Langebaan Lagoon in the 1990s, to around 20% of the number that occurred there in the 1980s. Numbers remained low in the 2000s. In addition, the percentage that remained during the austral winter (the breeding season in the Arctic) declined, and there was none during the period 2001–2009. This suggested that first-year birds, which largely comprise the austral winter population, were no longer travelling to southern Africa. The decline in numbers coincided with the decline in West Africa, but it was disproportionately larger in southern Africa. The observed pattern of change is consistent with a buffer effect, whereby southern Africa represents an extension to the range to less suitable habitat (requiring a 6 000 km extension to the migration) when the population size and competition is high in the main localities in West Africa. We are probably now witnessing the gradual decline in the number of adult birds who are fixed in their use of southern Africa as their non-breeding quarters.     

Life cycle of Marphysa sanguinea (Polychaeta: Eunicidae) in the Venice Lagoon (Italy)

The life cycle of a brackish water population of Marphysa sanguinea (Polychaeta Eunicidae), from the Venice Lagoon (Italy), was investigated from April 1993 to August 1994. Marphysa sanguinea is a large‐sized gonochoric species with annual iteroparous strategy and synchronous spawning at population level. The sex‐ratio was close to 1:1. There were no morphological differences between males and females and spawning occurred without epitokal metamorphosis. The gonadial activity was maximum during summer period in both sexes. From May to September in the females, the greater number of immature oocytes could be observed; starting from November immature oocytes decreased and progressively those with a wider diameter increased in number. Spawning took place in April–May and generally not all eggs were spawned, a small proportion being kept as a reserve material for the following gamete production. The pelagic phase (trochophore and metatrochophore stages) was short (2–3 days). The reduction in the dispersal phase, together with the development of a strong anterior musculature, brought to an early acquisition of the benthic habit, which was attained with the construction of the mucous tube inside of which the larva lived. The results highlighted that colonization of brackish environments took place thanks to morphological and physiological features that allow this species to live in a sediment layer characterized by the stability of the physical and chemical characteristics of the substratum.     

Effects of marine reserves on the reproductive biology and recruitment rates of commonly and rarely exploited limpets

We tested the effects of marine reserve status on the reproductive biology and recruitment rates of two commonly exploited (Helcion concolor, Scutellastra longicosta) and two rarely exploited (Cellana capensis, Scutellastra granularis) limpet species using two reserve and two non-reserve sites on the south coast of South Africa. Because densities of commonly exploited species are lower outside reserves, we hypothesised that limpets outside reserves will: (i) mature earlier; and (ii) show higher individual reproductive output. Rarely exploited species should show no such effects. For recruitment, we hypothesised that if recruits are attracted to adults or survive better where there are more adults, then commonly exploited (but not rarely exploited) species should show higher recruitment inside reserves. Analyses of gonadosomatic indices produced significant Month × Reserve interactions for all species (ANCOVA, p < 0.05), indicating inconsistent reserve effects even for exploited species, although months with significant differences occurred more often in the commonly exploited species, giving weak support to the hypothesis regarding reproductive output. Reserve status had no significant effect on sex ratios or size at sexual maturity for either sex of any species. Accordingly, reserves had only a minor influence on reproduction in these species, which might reflect an indirect effect of poor policing. The timing of major recruitment events differed among species, with two broad patterns: recruitment was sporadic for C. capensis and S. longicosta and protracted for H. concolor and S. granularis. Recruit densities showed strong site effects. Highest recruitment occurred at the exploited site, Xhora, with no reserve effects, except in a single month for C. capensis, indicating that recruitment is independent of whether the site is protected or not. Therefore, reserves do not enhance recruitment directly, but because these populations appear to be open on scales of tens of kilometres, generally higher densities of limpets within reserves could enhance overall recruitment, because of greater gamete output by the population. Accordingly, reserves might have an indirect ‘spillover’ effect on recruitment, if not a direct one.     

The reproductive style of Diplodus capensis (Sparidae) in southern Angola: rudimentary hermaphroditism or partial protandry?

The reproductive style of Diplodus capensis was examined in an unexploited coastal area in southern Angola. The mean length of females was significantly greater than that of males and, although not significant, females dominated the older age classes. The overall sex ratio was 1 male:4.7 females and female dominance increased with size. Histological analysis of gonads revealed that this species is a rudimentary hermaphrodite, with individuals possessing a non-functional bipotential ovotes-tis in the juvenile phase. Histological examination of the gonads of four macroscopically staged ‘intersex’ individuals suggested that they were functional males with a persistent ovarian portion in their gonads from the juvenile ovotestis. The heavily female-biased sex ratio and female dominance in the larger length classes are thought to be an alternative to sex change that is more resilient to exploitation when compared with the protandrous strategy displayed by the South African population of D. capensis.     

Variation in Surf-zone Fish Community Structure Across a Wave-exposure Gradient

Fluctuations in various attributes of a surf-zone fish community were examined by beach seining at a series of sites spanning a wave-exposure gradient in the Saldanha Bay–Langebaan Lagoon system, on the South African west coast. During April 1994, 24 species, totalling 25 676 individuals and 434 kg, were captured. Three teleosts,Atherina breviceps, Liza richardsoniiandPsammogobius knysnaensis, dominated numerically, while three elasmobranchs,Rhinobatos annulatus, Mustelus mustelusandMyliobatis aquila, dominated the biomass. Elasmobranchs displayed no discernible distribution patterns. Two important trends were, however, evident in the teleost catches: overall teleost abundance (mean density) increased markedly as wave exposure decreased; and highest species richness and diversity, and lowest dominance were both recorded at intermediate levels of exposure. A positive relationship between fish size and exposure was also evident for at least two of the species. These trends were attributed primarily to the availability and abundance of suitable food resources, and to physical disturbance introduced by breaking waves.     

South Africa's coastal-breeding white-breasted cormorants: population trends,breeding season and movements,and diet

White-breasted cormorants Phalacrocorax [carbo] lucidus breed around South Africa's coast and at inland localities. Along the coasts of the Northern, Western and Eastern Cape provinces, numbers breeding were similar during the periods 1977–1981 (1 116 pairs at 41 localities) and 2008–2012 (1 280 pairs at 41 localities). Along the coast of KwaZulu-Natal (not counted in 1977–1981), 197 pairs bred at nine localities in 2008–2012, when the overall number breeding around South Africa's coastline was about 1 477 pairs. Between the two study periods, numbers decreased in the Northern and Western Cape provinces following the loss of several breeding localities, but they increased in the Eastern Cape. In the Western Cape, however, numbers were stable east of Cape Agulhas and at nine well-monitored West Coast localities that were surveyed from 1978 to 2012. White-breasted cormorants breed throughout the year, with breeding at some localities more seasonal than at others and the timing of peaks in breeding varying at and between localities. In the vicinity of Saldanha Bay/Langebaan Lagoon (Western Cape), in Algoa Bay (Eastern Cape) and in northern KwaZulu-Natal, it is likely that birds moved between breeding localities in different years, although breeding often occurred at the same locality over several years. Human disturbance, presence of predators, competition for breeding space and occurrence of breeding by other waterbirds may influence movements between colonies. Securing sufficient good habitat at which white-breasted cormorants may breed will be important for conservation of the species. The species may breed at an age of 4 years, possibly younger. The bulk of their diet around South Africa's coast consists of inshore marine and estuarine fish species that are not intensively exploited by humans.     

Different sperm allocation strategies in two populations of the semiterrestrial crab Neohelice granulata (Brachyura,Grapsoidea, Varunidae)

Sperm reserves are costly to produce and so the development of different sperm allocation strategies may be advantageous. Knowledge of sperm allocation strategies is important from an evolutionary perspective because they contribute to characterize mating systems. However, population differences in sperm allocation strategies of the same species have rarely been assessed. Here, we studied the male sperm allocation strategies in two different populations of Neohelice granulata in Mar Chiquita Lagoon (MCL) and San Antonio Oeste (SAO), Argentina. We found that the quantity of ejaculate transferred by N. granulata males depended on different factors such as male size and female receptivity duration, while it was independent of female size, at both study areas. Regarding the operational sex ratio factor, the amount of ejaculate transferred depended on it in MCL but not in SAO. Thus, N. granulata males may have the capacity to regulate the quantity of ejaculate transferred based on individual factors such as their own size and female receptivity duration, and population factors such as operational sex ratio, which varies in the two populations studied.     

Variation in the size structure of corals is related to environmental extremes in the Persian Gulf

The size structure of coral populations is the culmination of key demographic events, including recruitment, mortality and growth, thereby providing important insights to recent ecological dynamics. Importantly, the size structure of corals reflects both intrinsic (inherent life-history characteristics) and extrinsic (enhanced mortality due to chronic or acute disturbances) forcing on local populations, enabling post-hoc assessment of spatial and taxonomic differences in susceptibility to disturbance. This study examined the size structure of four locally abundant corals (Acropora downingi, Favia pallida, Platygyra daedalea, and massive Porites spp.) in two regions of the Persian Gulf: the southern Gulf (Dubai and Abu Dhabi) and eastern Gulf (western Musandam). Significant and consistent differences were apparent in mean colony sizes and size-distributions between regions. All corals in the southern Gulf were significantly smaller, and their size structure positively skewed and relatively more leptokurtic (i.e., peaky) compared to corals in the eastern Gulf. Sea surface temperatures, salinity, and the recent frequency of mass bleaching are all higher, in the southern Gulf, suggesting higher mortality rates and/or slower growth in these populations. Differences in size structure between locations were more pronounced than differences between species at each location, suggesting that extreme differences in environmental conditions and disturbance events have a greater influence on population dynamics in the Gulf than inherent differences in their life-history characteristics.     

Patterns of distribution and abundance of the stalked barnacle (Pollicipes pollicipes) in the central and southwest coast of continental Portugal

The stalked barnacle Pollicipes pollicipes is a cirriped crustacean that lives on very exposed rocky shores. This barnacle is the most important economical resource on intertidal rocky shores of continental Portugal. It is highly prized as food and heavily exploited (professional and recreational fishery), but fishery data are scarce and do not estimate the real pressure upon this resource.Despite its socio-economic interest, specific regulations on this fishery are recent and different along the Portuguese coast. Four regions with different regulation can be identified: the marine reserve “Reserva Natural das Berlengas” (RNB) and the marine park “Parque Marinho Prof. Luiz Saldanha” (PMLS) (both in central Portugal); the natural park located in SW Portugal (“Parque Natural do Sudoeste Alentejano e Costa Vicentina”, PNSACV); and the rest of the coast.The main objective of the present study was to study the spatial patterns of percentage cover, biomass, density and size structure of P. pollicipes in areas with different exploitation regimes, including harvested areas and no-take areas. Additionally, variability between mid shore and low shore barnacles was also analysed.Seven areas were sampled with a variable number of sites (a total of 24) randomly sampled in each area during 2011. Photographs and image analysis (percentage cover) and destructive sampling (density, biomass and size) were used.In general, percentage cover, biomass and density were higher in mid shore when compared to low shore, namely in harvested areas. Low shore barnacles had a higher proportion of adults with moderate and high commercial value, while juveniles were relatively more abundant at mid shore.There were no consistent differences in the patterns of distribution and abundance of P. pollicipes among areas subject to different exploitation regimes. The most different area was the harvested area by professional fishers in RNB, where the highest biomass within the study was registered (mid shore, 7.7 kg·m^− 2). Barnacles within this area presented a higher proportion of adults with commercial value, while recruits and juveniles were relatively more abundant in other areas.The hypothesis of a highest percentage cover, density and biomass in the low shore of no-take sites was not supported.     

Preliminary results of a field study on some stress-related parameters in Tapes philippinarum naturally infected by the protozoan Perkinsus sp.

The aim of the present work was to investigate the possible use of the clam Tapes philippinarum—a filter-feeding bivalve living on soft bottoms—in the monitoring of sediment pollution in the Lagoon of Venice (North-East Italy). To this end, two clam populations, exposed to different environmental conditions (a relative clean site and an industrial polluted area), have been monitored for the prevalence of the protozoan parasite Perkinsus sp. as well as for several biological parameters commonly used as determinants of contaminants exposure. First results showed a low prevalence, higher in the clean site, but a very diffuse distribution of the parasite throughout the two populations. Nevertheless, greater digestive cells height and longer lysosomal latency time were observed in clams from the clean area. As for the physiological stress-related parameters, even if clearance rates were always higher in these clams, scope for growth values indicated a more complicated biological response.     

Catch, survey and life-history data for shrimp (Pandalus borealis) off Jan Mayen

The Jan Mayen area has an extreme environment with low temperatures and infrequent, but abrupt temperature changes. The shrimp population here is considered to be on its edge of distribution. The life-history parameters are in the same range as in other high-latitude shrimp populations and are characterized by slow growth, large size at maturation and extended longevity. Irregular and sporadic commercial exploitation limit fishing mortality and give the population life-history parameters not previously seen in other areas. The Jan Mayen shrimp are large compared to, e.g., the Barents Sea shrimp and can reach a maximum carapace length (L_max) of 37 mm and an age of 10–11 years. The large size at sex transformation (L₅₀, >24 mm) and analyses of length–frequency distributions indicate that the shrimp may be 6–7 years of age before changing sex. The change in L_max and L₅₀ observed during the study period is probably caused by increased natural mortality due to sudden temperature changes or due to increased predation, rather than increased growth rates. The life-history strategy of shrimp in the Jan Mayen area can be explained by factors such as depth, temperature and population density variations caused by fluctuation in recruitment and mortality.The shrimp fisheries in the Jan Mayen area began in the late 1970s and reached an annual landing of 2000 tonnes in 1985, and since then landings have oscillated around 500 tonnes depending on a combination of factors. The survey indices of stock biomass varied between 3000 and 6600 tonnes. For most years, the highest shrimp densities are at a depth of 200–299 m, while large shrimp (and therefore also female shrimp) are dominant at depths greater than 300 m.Fish community data were studied as the composition of the demersal fish community is an integrated response to environmental conditions and as predation affects the shrimp stock. Polar cod and capelin are the most abundant fish species in the study area. A high number of blue whiting was registered in 1979, but the number declined in 1980 and 1981 as temperature decreased. During the surveys in 1994 and 1995, no blue whiting was registered. A few individuals were found again in the 1999 samples. The number of Greenland halibut has declined from the beginning of the 1980s to the 1990s.     

Use of particle-size data to predict potential pelagic-fish yields of some southern African areas

A particle-size spectrum model is used to estimate standing stocks of some pelagic fish from measurements of phytoplankton chlorophyll in two exploited regions in southern Africa (southern Benguela and off South West Africa/Namibia) and in two unexploited regions (the Agulhas Bank and off the eastern Cape Province). The model is based on the assumption that equal biomasses occur in logarithmically equal size classes in the pelagic marine environment. Phytoplankton, with an equivalent spherical diameter ranging from 1 to 128 μm, occupy 21 size classes on the logarithmic scale. Two different size ranges are assumed for some commercial, pelagic fish species, equivalent to exploitation with two different purse-seine mesh sizes. A mesh of 12,7 mm would catch 8 size classes of pilchard, horse mackerel and anchovy whereas a mesh of 32 mm would catch only 3,3 size classes of pilchard and horse mackerel. From the model, the potential biomass of these commercial pelagic fish is estimated, after allowing for the presence of other commercial and non-commercial fish and other taxa in the exploited size range. Total pelagic fish production is estimated by assuming constant turnover rates of 1·y^?1 and 1,5·y^?1 when exploited with 32 and 12,7 mm mesh nets respectively. Consideration of the maximum and mean reported catches in the exploited areas indicates that only some 25 per cent of pelagic fish production is exploitable by man. On this basis, the unexploited Agulhas Bank region may yield some 400 000 metric tons (wet) of pelagic fish of the species considered, and the East Coast region some 90 000 tons. Exploitation in these regions cannot be recommended, because the Agulhas Bank is an important spawning ground for many pelagic species, and the fish in both regions probably act as a reserve buffer for the heavily exploited pelagic resource of the Western Cape.     

Interactions between Zostera capensis and Callianassa kraussi: influences on community composition of eelgrass beds and sandflats

Eelgrass beds have been postulated to support different faunal communities from unvegetated sandflats, in part because of the stabilisation of sediments in eelgrass beds and their destabilisation in sandflats due to bioturbation. More specifically, eelgrass beds have been hypothesised to support disproportionately greater numbers of small, flexible and non-burrowing species, and bioturbated sandflats to support more large, hard-bodied burrowers. These concepts were tested in Langebaan Lagoon on the west coast of South Africa, where beds of the eelgrass Zostera capensis and sandflats dominated by Callianassa kraussi bioturbation are mutually exclusive. In eelgrass beds, sediment penetrability was significantly reduced compared to that in sandflats. Distinctly different faunal communities occurred in the two habitats, and the suite of species characteristic of each was consistent between years and between sites. Overall, density was higher in eelgrass beds than in sandflats. In contrast to previous studies, however, richness and diversity in sandflats were greater than, or equal to, values for eelgrass beds. There is convincing support for the hypothesis that burrowers are more prevalent in sandflats and less prevalent in eelgrass beds. Conversely, body flexibility does not differ between habitats and sizes are greater in the eelgrass beds than in the sandflats.     

Textural characteristics and morphosedimentary environment of foreshore zone along Ganpatipule,Maharashtra, India

The cross-shore profile and the textural distribution of foreshore sediments of Ganpatipule beach along Maharashtra coast covering two annual cycles are examined. Ganpatipule beach depicts erosion and accretion of the berm, reduction and widening of foreshore widths during the monsoon (June–September) and post-monsoon (October–May), respectively with net sediment accretion during the study period due to the changes in the wave characteristics. A direct correlation is observed between the median sediment grain size and beach-face slopes signifying high wave energy ensuing to a gentle to very gentle slope. The sediments are mainly medium grain size, moderately well sorted, bimodal, very fine skewed to very coarse skewed and very platykurtic to very leptokurtic in nature. The binary plots of the textural parameters (mean, skewness, kurtosis, and standard deviation) depicted a characteristic beach environment of deposition. The study shows that the sediment is concentrated in the environment of rolling and bottom suspension. The study on grain size distribution of sediments could be used to assess the wave energy condition prevailing along the coastal area.     

Population Structure of Blennius incognitos BATH 1968 (Pisces: Teleostei: Blen-niidae) during the Reproductive Period with Comments on Age and Growth of Small Benthic Littoral Fishes

Abstract. Length frequency distribution, condition factor and parasite infection of Blennius incog-nitus from three different areas near Rovinj, Yugoslavia have been investigated. Differences between considered parameters in three populations of B. incognitus have been found and discussed. Fishes were aged by otolith reading. Mean life span, growth rate, sex ratio and a sexual dimorphism in body size were noted in this littoral blenny. Our findings are discussed and compared with data on comparable littoral fishes.     

Otolith reading and multi-model inference for improved estimation of age and growth in the gilthead seabream Sparus aurata (L.)

Accurate knowledge of fish age and growth is crucial for species conservation and management of exploited marine stocks. In exploited species, age estimation based on otolith reading is routinely used for building growth curves that are used to implement fishery management models. However, the universal fit of the von Bertalanffy growth function (VBGF) on data from commercial landings can lead to uncertainty in growth parameter inference, preventing accurate comparison of growth-based history traits between fish populations. In the present paper, we used a comprehensive annual sample of wild gilthead seabream (Sparus aurata L.) in the Gulf of Lions (France, NW Mediterranean) to test a methodology improving growth modelling for exploited fish populations. After validating the timing for otolith annual increment formation for all life stages, a comprehensive set of growth models (including VBGF) were fitted to the obtained age–length data, used as a whole or sub-divided between group 0 individuals and those coming from commercial landings (ages 1–6). Comparisons in growth model accuracy based on Akaike Information Criterion allowed assessment of the best model for each dataset and, when no model correctly fitted the data, a multi-model inference (MMI) based on model averaging was carried out. The results provided evidence that growth parameters inferred with VBGF must be used with high caution. Hence, VBGF turned to be among the less accurate for growth prediction irrespective of the dataset and its fit to the whole population, the juvenile or the adult datasets provided different growth parameters. The best models for growth prediction were the Tanaka model, for group 0 juveniles, and the MMI, for the older fish, confirming that growth differs substantially between juveniles and adults. All asymptotic models failed to correctly describe the growth of adult S. aurata, probably because of the poor representation of old individuals in the dataset. Multi-model inference associated with separate analysis of juveniles and adult fish is then advised to obtain objective estimations of growth parameters when sampling cannot be corrected towards older fish.     

Movement patterns of the parrotfish Sparisoma cretense in a Mediterranean marine protected area

Understanding the movements of exploited fish has become a major concern for several management and conservation initiatives, such as the implementation of well designed marine protected areas. Movements of an important recreational target species from the Mediterranean Sea, the parrotfish Sparisoma cretense, were determined in a marine protected area using passive acoustic telemetry, to evaluate site fidelity and homing, quantify home range and identify temporal patterns. Six adult parrotfish (20.8–29.8 cm total length) were caught along the north-eastern coast of Lampedusa (Italy) and surgically implanted with acoustic transmitters. Three fish were caught and released at the same site within the integral (i.e. “no entry-no take”) reserve, whereas the others were caught outside the reserve boundary and released at the mid reserve 0.5 km apart. Two of the three fish that were released away from the capture site demonstrated homing abilities. Four fish showed a strong site fidelity, whereas the others moved frequently in and out of the monitoring area. Home range sizes estimated over the period of monitoring (up to 207 days) varied from 70,387 to 256,398 m², with core areas of 16,688 to 84,946 m². Home range size did not differ significantly between day and night. Home ranges of all fish extended beyond the reserve boundaries, showing example of potential spillover into take zones. Temporal activity patterns of fish were diurnal with a dominant diel rhythm, likely due to a resting behaviour at night. Though not specifically designed to protect exploited fish, the marine reserve of Lampedusa seems adequate for the conservation and management of S. cretense.