Isolation and characterization of polymorphic microsatellite markers in Pagellus bogaraveo,and cross‐species amplification in Sparus aurata and Dicentrarchus labrax

Several new fish species are currently being included in breeding programmes. However, as specific molecular markers have not yet been developed, this represents a commercial handicap with respect to traditional aquaculture species such as gilthead sea bream or Atlantic salmon. In the present study, 12 new microsatellite loci were developed for blackspot sea bream (Pagellus bogaraveo) that show high levels of polymorphism, especially useful in parentage assignment and individual identification. In addition, cross‐amplification was obtained for two important species for Spanish aquaculture, gilthead sea bream and sea bass.     

Implications for catch composition and revenue in changing from diamond to square mesh codends in the northeastern Mediterranean

The objective of this study was to estimate the potential short‐term economic loss as a result of replacing the commercial diamond codend with a square mesh codend, and to compare fish lengths captured in 40 mm square (S40) vs 44 mm commercial hand‐woven diamond (CD44) mesh codends for red mullet (Mullus barbatus), common pandora (Pagellus erythrinus), bogue (Boops boops), European hake (Merluccius merluccius), axillary seabream (Pagellus acarne), and brushtooth lizardfish (Saurida undosquamis). A total of 20 hauls (10 hauls for S40 and 10 hauls for CD44) were conducted onboard a commercial trawler between 27 February and 11 April 2012 in Mersin Bay in the northeastern Mediterranean. Results showed that the 40 mm square mesh codend caught significantly fewer juveniles of all aforementioned species. However, when changing from the commercial diamond codend to the 40 mm square mesh codend the potential economic loss of revenue was found to be 40% in the study period, which covered the final 6 weeks of the fishing season.     

Selectivity of diamond (PA) and square (PE) mesh codends for commercially important fish species in the Antalya Bay,eastern Mediterranean

Size selectivity of the 40 mm nominal polyethylene (PE) square mesh codend and the 44 mm nominal polyamide (PA) diamond mesh codend were determined under commercial conditions in the demersal trawl fishery. Data were collected using the covered codend technique and analyzed by logistic equation with a maximum likelihood method. Changing the mesh from a 44 mm PA diamond to a 40 mm PE square increased the mean retention lengths (L₅₀s) of red mullet (Mullus barbatus), picarel (Spicara maena) and bogue (Boops boops) and decreased the selection ranges (SR) for common pandora (Pagellus erythrinus). For large‐eye dentex (Dentex macrophthalmus) and axillary sea bream (Pagellus acarne) mean L₅₀ and SR values were 9.6 and 11.8, and 2.4 and 2.4 cm, respectively, only in the DM44PA codend. For golden banded goatfish (Upeneus moluccensis) values for SM40PE were only 15.0 and 2.7 cm, respectively. Results showed that the 40 mm PE square mesh codend provided higher selectivity for most of the Mediterranean fishes. The results also showed that regulating mesh size and requiring square mesh openings during trawling is essential for the release of immature individuals. This practice will result in a reduction in overfishing and permit recovery of overfished stocks.     

Seasonal variation in the trawl codend selectivity of common pandora (Pagellus erythrinus)

Seasonal changes in the selectivity of a 40 mm polyethylene trawl codend for common pandora (Pagellus erythrinus) were tested under similar fishing conditions in spring, summer and autumn 2002, and winter 2003. Data were obtained using the covered codend technique and analyzed using a logistic model fitted with the maximum likelihood method. Parameters of mean curves for each trip were estimated by using Fryer’s between‐haul variation model. To determine seasonal changes in the condition of the fish, samples were taken to cover the entire length range of the catch along with length measurements to the nearest mm and weights to the nearest 0.1 g. Results showed a tendency for decrease in selectivity from summer (L₅₀ = 11.3 cm, SR = 2.2 cm) and autumn (L₅₀ = 11.2 cm, SR = 1.7 cm) to winter (L₅₀ = 10.7 cm, SR = 2.4 cm) and spring (L₅₀ = 10.2 cm, SR = 2.9 cm). Potential effects of water temperature, fish condition, population size structure, and gonad developments on selectivity are discussed to explain the seasonal variation in trawl codend selectivity.     

Dynamics of black spot sea bream (Pagellus bogaraveo) mean length: evaluating the influence of life history parameters, recruitment, size selectivity and exploitation rates

Stochastic simulations were used to evaluate the influence of recruitment pattern (log‐normal, decreasing), size selectivity (normal, logistic model) and fishing mortality pattern (abrupt, continuous increase in fishing mortality) on the evolution of mean length and the dispersion of mean length for a relatively long‐lived deep‐water species, the black spot sea bream (Pagellus bogaraveo). An abrupt increase in fishing mortality resulted in mean size decreasing and stabilizing at a lower level while a steady increase in fishing mortality caused the continuous decrease in mean size that has been reported for many long‐lived species. Decrease in mean size was greatest for logistic model simulations and for cases where fish were susceptible to capture at a small size. Logistic selectivity, with decreasing recruitment and increasing fishing mortality over time, resulted in mean length and variability in mean length trends similar to that observed for the Strait of Gibraltar fishery. Furthermore, it was found with the declining recruitment that moderate increases in fishing mortality can result in significant decreases in mean length. Given the importance of mean size as an indicator of the state of a resource, these simulations are a useful alternative or complement to standard fisheries assessment methods, helping to provide information on exploitation patterns and rates that can be used for conservation and management.     

Sorting grid trials to improve size selectivity of red mullet (Mullus barbatus) and annular sea bream (Diplodus annularis) in Turkish bottom trawl fishery

Sorting grids with two different bar spacings (12 mm and 14 mm) were tested to improve size selectivity of the commercially important fish species, red mullet (Mullus barbatus) and annular sea bream (Diplodus annularis), in Turkish bottom trawl fishery. Fishing trials were carried out with R/V ‘Egesüf’ between April and May 2003 in Izmir Bay, Aegean Sea, using a traditional bottom trawl. Selectivity data were collected by the top cover method and analyzed by means of a logistic equation with the maximum likelihood method. Selectivity parameters for individual hauls were obtained with the software program cc 2000 . Mean selectivity was also estimated and compared using the EC Model software that takes between‐haul variations into account. The codend catch size as an additional explanatory variable was used in the comparison. The Kolmogorov–Smirnov (K–S) test was also applied to detect differences between length‐frequency distributions in the upper and lower bags of the 12 and 14 mm bar spacings for red mullet and annular sea bream. The mean L₅₀ values of red mullet were 8.7 and 10.0 cm with the 12 and 14 mm grids, respectively. The L₅₀ value of 14 mm was comparable with the L₅₀ value of the codend mesh size; however, the 12 mm value was rather low. The mean L₅₀ values of 12 and 14 mm bar spacings were 8.8 and 10.4 cm for annular sea bream, respectively; the value of 14 mm bar spacing was very close to 50% size at sexual maturity of the species (10.5 cm). The K–S test indicated length distributions of red mullet and annular sea bream in the 12 and 14 mm upper and lower bags as significantly different (P < 0.05). These results show that improving the size selectivity in a multi‐species fishery using a single selective device is rather difficult. However, higher size selectivity can be obtained when considering the minimum landing size or the 50% sexual maturity size for a given species.     

Food partitioning and diet temporal variation in two coexisting sparids, Pagellus erythrinus and Pagellus acarne

Resource partitioning in two congeneric sparids, pandora Pagellus erythrinus and axillary seabream Pagellus acarne, was investigated using stomach content analysis integrated with data on stable isotopes (δ(15) N and δ(13) C). The study was carried out on coastal muddy bottoms in the Gulf of Castellammare (southern Tyrrhenian Sea, western Mediterranean Sea) in seasons (autumn, November 2004; winter, March 2005; spring, early June 2005), at depths between 50 and 100 m. Stomach content analysis suggested low trophic niche overlap between the two species. Pagellus erythrinus mainly preyed on strictly benthic organisms (polychaetes, brachyuran crabs and benthic crustaceans). Although it consumed benthic prey, P. acarne preferred suprabenthic prey such as peracarid crustaceans from the benthic boundary layer a few metres above the bottom. The two species showed different isotopic values, with P. erythrinus exhibiting higher δ(15) N and more enriched δ(13) C than P. acarne, in accordance with its marked benthic behaviour and high predation on carnivore polychaetes. Significant temporal variability in both diet and isotopic values caused trophic differences between the two species. The autumn and winter diet differed from the spring diet and the trophic levels of both species increased from autumn and winter to spring, in accordance with variations in food availability and changes in prey δ(15) N and δ(13) C. These temporal variations may be linked to an increase in energy requirements for reproduction, together with the differing availability of preferred prey throughout the year. Significantly, lower δ(13) C was recorded in fishes collected in winter (March), suggesting the influence of river inputs as a source of particulate organic matter in this zone after the flooding season. In conclusion, these sympatric congeneric fish species displayed clear food partitioning throughout the temporal scale analysed.     

Morphometric characterization of sharpsnout sea bream (Diplodus puntazzo) and gilthead sea bream (Sparus aurata) spermatozoa using computer-assisted spermatozoa analysis (ASMA)

As part of a larger study on sperm quality and cryopreservation methods, the present study characterized the head morphometry of sharpsnout sea bream (Diplodus puntazzo) and gilthead sea bream (Sparus aurata) spermatozoa, using both scanning electron microscopy (SEM) and computer‐assisted morphology analysis (ASMA). The latter method has been used rarely in fish and this is its first application on sharpsnout sea bream and gilthead sea bream spermatozoa. Results obtained using SEM are expensive and time‐consuming, while ASMA provides a faster and automated evaluation of morphometric parameters of spermatozoa head. For sharpsnout sea bream spermatozoa, similar head measurement values were obtained using both ASMA and SEM, having a mean ± standard error length of 2.57 ± 0.01 μm vs 2.54 ± 0.02 μm, width of 2.22 ± 0.02 μm vs 2.26 ± 0.04 μm, surface area of 4.44 ± 0.02 μm² vs 4.50 ± 0.04 μm² and perimeter of 7.70 ± 0.02 μm vs 7.73 ± 0.04 μm using ASMA and SEM, respectively. Although gilthead sea bream spermatozoa were found to be smaller than those of sharpsnout sea bream, spermatozoal head morphometry parameters were also found to be similar regardless of evaluation method, having a mean head length of 1.97 ± 0.01 μm vs 1.94 ± 0.02 μm, head width of 1.80 ± 0.01 μm vs 1.78 ± 0.02 μm, surface area of 3.16 ± 0.03 μm² vs 3.18 ± 0.06 μm² and perimeter of 6.52 ± 0.04 μm vs 6.56 ± 0.08 μm using ASMA and SEM, respectively. The results demonstrate that ASMA can be considered as a reliable technique for spermatozoal morphology analysis, and can be a useful tool for studies on fish spermatozoa, providing quick and objective results.     

Occurrence and prevalence of Philometra filiformis (Stossich, 1896) on Pagellus erythrinus (Linnaeus, 1758) in the Southern Tyrrhenian Sea

In this paper the host‐parasite relationship between Philometra filiformis and the common pandora Pagellus erythrinus from the Southern Tyrrhenian Sea were studied. A total of 305 (257 females and 48 males) specimens of common pandora were sampled from June 2009 to April 2011 from commercial landings as well as from bottom trawl surveys. A total of 39 P. erythrinus were parasitized (mean prevalence, P = 12.80%; mean abundance, A = 0.19), with the parasite occurring throughout the study area and with wide fluctuations in prevalence values ranging from 0 to 28.60%. Prevalence increased with age of the host, with most parasites (27.78%) found in the older common pandora whereby P. filiformis parasitized only the females. A significant correlation between prevalence, abundance and maturity stages of the fish was evident, with most parasites found in mature/spawning specimens. The varying degrees of gonadic damage caused by this nematode reveal a serious threat to the reproductive success of P. erythrinus.     

A preliminary investigation of allozyme genetic variation and population structure in common pandora (<Emphasis Type="Italic">Pagellus erythrinus</Emphasis>, Sparidae) from Tunisian and Libyan coasts

The genetic characterization of natural populations of common pandora (Pagellus erythrinus, Sparidae) was studied using allozyme markers. Fish samples (n = 360) were collected from five locations along the Tunisian coasts and one from the Libyan coast. From eight enzymatic systems, 12 putative enzyme-coding loci were resolved, 8 of which were polymorphic at a level of 99%. F statistics indices revealed a significant departure from panmixia with heterozygote deficiencies and a slight genetic differentiation between samples. Neighbor-joining dendrogram constructed by Reynolds genetic distance showed that the populations sampled from the southeastern Mediterranean Sea were more differentiated from the others.     

Inter- and intra-researcher variation in measurement of morphometrics on Steller sea lions (<Emphasis Type="Italic">Eumetopias jubatus</Emphasis>)

Substantial effort has been made to increase the accuracy of photogrammetric measurement techniques, especially on marine mammals. However, accuracy of the physical measurements is rarely considered when calculating the photogrammetric accuracy. We examined inter- and intra-researcher variation in the measurement of physical morphometrics of Steller sea lions (Eumetopias jubatus) to assess their potential effects on photogrammetric accuracy and body mass predictions based on photogrammetrically derived morphometrics. Significant differences were found inter-researcher in median standard length and axillary girth and intra-researcher when measuring axillary girth of the same animals. Photogrammetrically derived estimates of these parameters are comparable to physical measurements when taking into account the inherent inter- and intra-researcher variation.     

Successful fertilization and hatching of four European cyprinid species using cryopreserved sperm

In this study we tried to develop a uniform method of sperm cryopreservation for four cyprinid fish species indigenous to Hungarian waters: the roach (Rutilus rutilus L.), the bream (Abramis brama L.), the silver bream (Blicca bjoerkna L.) and the barbel (Barbus barbus L.). The sperm was frozen in liquid nitrogen vapor in the presence of five extenders (350 mm fructose, 30 mm Tris, pH 8.0; 350 mm glucose, 30 mm Tris, pH 8.0; 300 mm sucrose, 30 mm Tris, pH 8.0; 200 mm KCl, 30 mm Tris, pH 8.0 and modified Kurokura's extender) and two cryoprotectants: 10% methanol (MeOH) and 10% dimethyl‐sulfoxide. The highest post‐thaw motility (roach: 77 ± 6%, bream: 77 ± 6%, silver bream: 67 ± 5%, barbel: 75 ± 6%), fertilization (roach: 84 ± 4%, bream: 83 ± 2%, silver bream: 63 ± 2%, barbel: 70 ± 4%) and hatching (roach: 74 ± 2%, bream: 67 ± 6%, silver bream: 54 ± 2%, barbel: 61 ± 4%) rates were found when either fructose or glucose extenders were used in combination with MeOH as cryoprotectant for all four investigated species. Strong correlations were found between post‐thaw motility of the sperm and fertilization or hatching rates, which indicates that motility can be used to predict fertilization success in these species.     

Genetic integrity of black sea bream (Acanthopagrus schlegeli) sperm following cryopreservation

Although semen cryopreservation has been applied successfully in many fish species, extensive variation in post‐thaw semen quality exists between species and individuals. AFLP (amplified restriction fragment length polymorphism) is a powerful method for detecting DNA polymorphisms at the individual, population, and species levels. The method has been successfully applied to boars (Sus domestica, Suidae, Artiodactyla, Mammalia) to detect and evaluate differences in DNA sequences that correspond with semen integretiy after employing various freezing techniques. Freezing and thawing of semen has also an effect of selecting for freezing‐resistant (or intact) and eliminating non‐viable or defective sperm. Only the fully intact and functional sperm, despite potential compromise by adverse freezing and osmotic stresses, retain fertility after thawing. The objective of this study was to use AFLP to assess any genetic changes associated with the effect of employed cryo‐methodology on the genetic integrity of sperm of the black sea bream (Acanthopagrus schlegeli) under different cryopreservation treatments. The cryopreservation protocols had no significant effect on sperm motility or survival rate of fertilized ova regardless of using fresh (% motile sperm 89.6 ± 3.0; % embryonic survival rate 54.4 ± 2.9) and frozen‐thawed semen (% motile sperm 80.2 ± 2.0; % embryonic survival rate 51.8 ± 2.0). The post‐thaw sperm motility and survival rates were not significantly different among the sperm samples of the five black sea bream males examined. In the present study, the remaining black sea bream sperm that survive the cryopreservation limit the power of AFLP to trace the genetic markers which correlate with the differences in the sensitivity of sperm to cryo‐injury. It is also possible that point mutations outside the AFLP priming sites may not have been detected. More thorough investigations are needed to determine whether such DNA fingerprints would be found in fish species.     

Distribution and biological features of the common pandora,Pagellus erythrinus (Linnaeus, 1758), in the southern Tyrrhenian Sea (Central Mediterranean)

A synthetic analysis of the distribution, abundance and some biological traits of the common pandora (Pagellus erythrinus) was performed. Data were gathered in 15 experimental bottom trawl surveys carried out off the southern Tyrrhenian Sea from 1994 to 2008. A total of 2,166 P. erythrinus were found in the investigated area, with a preference for the upper continental shelf (10–100 m). The highest persistence was recorded in the trawl-banned areas. The sex ratio Sr = F/(F + M) ranged between 0.60 and 0.96 (overall 0.78). The size at which 50 % of the individuals were mature was 157 and 170 mm total length for females and males, respectively. The length–weight relationship for all individuals was described by the following parameters: a = 0.016 and b = 2.905. Growth was evaluated (sexes combined) by applying length-based methods; up to eight significant modal components were evidenced. The von Bertalanffy growth parameters for the whole population were estimated at L _∞ = 454 mm, K = 0.08 and t ₀ = ?2.57. The present results are in agreement with the information available for the other Mediterranean stocks suggesting common biological features.     

Temporal change in the morphometry–body mass relationship of polar bears

Accurate information on animal body mass is often an essential component of wildlife research and management. However, for many large-bodied species, obtaining direct scale weights from individuals may be difficult. In these cases, morphometric equations (e.g., based on girth or length) may provide accurate and precise estimates of body mass. We developed predictive equations to estimate the body mass of free-ranging polar bears (Ursus maritimus) in western Hudson Bay, Canada. Using multiple linear and non-linear regression, we identified a strong relationship between polar bear body weight and linear measures of straight line length and axillary girth. The mass–morphometry relationship appeared to change over time and we developed separate equations for polar bears measured during 2 time periods, 1980–1996 and 2007–2009. Non-linear models were more accurate and provided body mass estimates within 5.8% (R² = 0.98) and 6.1% (R² = 0.98) of scale weight in the earlier and later time periods, respectively. Earlier equations developed for polar bears in this subpopulation performed poorly when applied to recently sampled individuals. In contrast, some contemporary equations from other regions performed reasonably well, suggesting that temporal changes within a subpopulation may be more pronounced than regional differences and can render earlier predictive equations obsolete. Our results have important implications for current and future studies of polar bear body condition and the effects of ongoing climate warming. © 2011 The Wildlife Society.     

Morphometric comparison and differentiation between artificially-released and wild red sea bream (Pagrus major)

The objective of this study is to develop a method of differentiation of hatchery-reared and artificially-released red sea bream (Pagrus major) from wild fish, based upon their morphometric differences. Morphometric measurements were done on fork length and 14 other characters. Among these charac)ters, significant differences between hatchery-reared and wild red sea bream were observed in body height, height at eye, eye diameter and upper jaw length. Discriminant functions were effective in differentiating artificial fish from wild fish.     

Stress reactivity and adiposity of youth

Objective: The relationship between stress reactivity and total or central adiposity in children has not been widely studied. Data from two studies were combined to determine the relationship between reactivity to interpersonal stress and the adiposity of children. Research Methods and Procedures: Stress reactivity to an interpersonal stressor (speech) was measured in 36 boys (9.8 ± 1.3 years of age) and 27 girls (9.3 ± 1.3 years of age). Total adiposity (percentage body fat) was estimated from skinfolds and central adiposity from the abdominal girth. Multiple regression was used to establish the associations of change in perceived stress and heart rate reactivity with adiposity. Age, sex, ethnicity, and baseline perceived stress and heart rate served as covariates for total adiposity. Fat mass was included as an additional covariate for the prediction of log abdominal girth (central adiposity). Results: Based on adjusted β‐weights, change in perceived stress (β = 1.13, p ≤ 0.001) and heart rate reactivity (β = 0.14, p ≤ 0.03) independently predicted percentage body fat. Heart rate reactivity (β = 0.002, p ≤ 0.04) independently predicted log abdominal girth. Discussion: Reactivity to psychological stress may initiate the antecedents of cardiovascular disease before adolescence by increasing total and central adiposity. Future studies should determine whether stress reactivity increases the adiposity of youth by increasing their consumption of energy‐dense snack foods and decreasing their willingness to be physically active.     

A comparison of fatty acid,cholesterol and vitamin composition in sea bass [Dicentrarchus labrax (Linnaeus, 1758)] and sea bream [Sparus aurata (Linnaeus, 1758)] from three cage farm areas: Antalya and Muğla (Turkey) and İskele (Northern Cyprus)

In the present study the fatty acids, cholesterol and vitamin composition in farmed sea bass (8 fish per species per farm; weight range: 389.6–395.8 g, total length range: 297–316 mm) and sea bream (8 fish per species per farm; weight range: 386.8–391.7 g, total length range: 263–268 mm) from three cage farms (?skele in northern Cyprus, Antalya and Mu?la in Turkey) were compared during the harvesting period in June–July 2011. The results showed that the muscles of D. labrax and S. aurata farmed fish were rich in n‐3 fatty acids, but with important differences. For example, the muscles of sea bass farmed in ?skele were rich in docosahexaenoic acid (DHA) and n‐3 polyunsaturated fatty acids (PUFA). Palmitic acid (C16:0) was the primary saturated fatty acid, and oleic acid (C18:1 n‐9) the primary monounsaturated fatty acid in the muscle and liver samples of the cage‐farmed sea bass and sea bream. There were no significant differences in the cholesterol content in the muscles of sea bream farmed in ?skele, Antalya or Mu?la. In conclusion, the n‐3/n‐6 ratio in the muscle of farmed S. aurata and D. labrax is within the recommended limits for a healthy human diet, being very suitable for human nutrition.     

The ontogeny of the alimentary tract of larval pandora, Pagellus erythrinus L.

The ontogenesis of the alimentary tract and its associated structures (liver, pancreas, gall bladder) was studied in common pandora Pagellus eythrinus L., a promising species for diversification in Mediterranean aquaculture. Mass production of pandora has been limited so far by high larval and juvenile mortalities, which appear to be related to nutritional deficiencies. The development of the larval digestive system was studied histologically from hatching (0 DAH) until day 50 (50 DAH) in reared specimens, obtained by natural spawning from a broodstock adapted to captivity. At first feeding (3–4 DAH) both the mouth and anus had opened and the digestive tract was differentiated in four portions: buccopharynx, oesophagus, incipient stomach and intestine. The pancreas, liver and gall bladder were also differentiated at this stage. Soon after the commencement of exogenous feeding (5–6 DAH), the anterior intestinal epithelium showed large vacuoles indicating the capacity for absorption of lipids, whereas acidophilic supranuclear inclusions indicating protein absorption were observed in the posterior intestinal epithelium. Both the bile and main pancreatic ducts had opened in the anterior intestine, just after the pyloric sphincter, at this stage. Intestinal coiling was apparent since 4 DAH, while mucosal folding began at 10 DAH. Scattered mucous cells occurred in the oral cavity and the intestine, while they were largely diffused in the oesophagus. Gastric glands and pyloric caeca were firstly observed at 28 DAH and appeared well developed by 41 DAH, indicating the transition from larval to juvenile stage and the acquisition of an adult mode of digestion.     

Isolation and characterisation of new polymorphic microsatellite markers for the striped sea bream (Lithognathus mormyrus)

The striped sea bream (Lithognathus mormyrus) is a coastal marine teleost of commercial importance from the family Sparidae, for which information on stock boundaries is currently lacking. We developed two multiplex PCR for the collective screening of nine polymorphic microsatellite markers for this species. Five primer pairs are specific to L. mormyrus, the remaining four are identical to previously isolated sequences in Sparus aurata and Pagellus bogaraveo. The number of alleles among 40 individuals from the Western Mediterranean ranged from 8 to 20 and observed heterozygosity values ranged between 0.65 and 0.92. F _ST estimate obtained between two separate geographic locations indicate that the loci should prove very useful to study genetic population structure in L. mormyrus.