Occurrence of tripletail Lobotes surinamensis (Bloch, 1790) in the inner Bristol Channel,UK

A specimen of tripletail Lobotes surinamensis (total length: 402 mm, total mass: 1262 g) was caught in the shallow waters of the inner Bristol Channel on September 2, 2019, with this only the second known capture of this species from the British Isles. Given the cosmopolitan distribution of this species, the potential origin of this specimen is uncertain.     

Occurrence of Lobotes surinamensis (Osteichthyes: Lobotidae) in the Mediterranean: Historical and recent data

This paper provides a review of the current status and historical distribution of Lobotes surinamensis in the Mediterranean Sea. Thirty two records were compiled for the period between 1968 and 2016, which shows that the species is in the Mediterranean much more abundant than previously understood.     

Diet of the Atlantic bonito Sarda sarda (Bloch, 1793) in the Northeast Aegean Sea

Seasonal and size‐related patterns in feeding habits of the Atlantic bonito (Sarda sarda) in the Northeast Aegean were investigated over a 2‐year period May 2007 – May 2009 based on analysis of stomach contents of 134 fish ranging from 266–655 mm fork length. The fish were caught by purse‐seine boats operating around the islands of Lesvos and Chios (Greece). Of the stomachs examined, 46% contained at least one prey item and significant seasonal and size‐related patterns were found in the occurrence of non‐empty stomachs. The overall diet composition in terms of numerical importance was 71% fish, 28% crustaceans and 1% cephalopods. Of the fish, Engraulidae (Engraulis encrasicolus) were the dominant prey taxon, followed by Centracanthidae (Spicara spp.) and then Clupeidae (Sardina pilchardus). Statistically significant monthly variation in diet was apparent, suggesting that S. sarda take advantage of seasonally abundant prey fish in the study area, but no size‐related variation in the importance of the main prey species was detected.     

Cryopreservation of giant grouper Epinephelus lanceolatus (Bloch, 1790) sperm

The grouper, Epinephelus lanceolatus, is a vulnerable species of high economic value. An effective protocol was developed for the cryopreservation of E. lanceolatus by comparing different extenders produced by mixing various cryoprotectants (dimethyl sulfoxide, methanol and glycerol) and diluents (MPRS, TS‐2, TS‐19, Cortland and Hank's). Using computer‐assisted sperm analysis (CASA) and morphological analysis, the sperm motility and fertilization rates from post‐thaw sperm were comparable to untreated controls. The results revealed that MPRS (containing 12% DMSO) or TS‐19 (containing 12% DMSO), were the optimum extenders for protecting the sperm from cryo‐damage in liquid nitrogen. The post‐thaw sperm maintained high motility (90.61 ± 3.03%) and a fertilization rate (92.27 ± 2.43%) similar (P > 0.05) to fresh sperm (94.34 ± 4% and 94.10 ± 1.87%). This study is the first to report on the successful sperm cryopreservation of E. lanceolatus and provides an important tool for repopulating this species through aquaculture.     

Age and growth of Atlantic bonito (Sarda sarda Bloch, 1793) in the Sea of Marmara and Black Sea,Turkey

Age and growth of Atlantic bonito (Sarda sarda Bloch, 1793) were determined in the Black Sea and Sea of Marmara from October 2003 to May 2005. A total of 694 samples ranging from 23.5 to 71 cm total length was collected; age estimates were carried out on otoliths of 248 fish. Male and female fish ages were estimated as up to 3⁺. The length–weight relationship and the von Bertalanffy growth curve (TVBGF) were described for all individuals as: W = 0.0054L^3.215 and L_t = 68.01 [1 ? e^{?0.895 (t + 0.395)}]. These data are discussed in relation to other growth studies of S. Sarda in the Mediterranean Sea.     

The relationship between otolith size and estimated age of tigertooth croaker (Otolithes ruber Bloch and Schneider, 1801) in Oman Sea,Iran

The relationships between somatic growth and otolith dimensions, otolith size to estimated age and growth parameters of the tigertooth croaker (Otolithes ruber) were investigated in 100 specimens (size range: 19.1–52.0 cm, total length) from the Oman Sea area, September 2014. All 100 otoliths were sectioned and determined by age. The oldest specimen was a 4.5‐year‐old female with a total length of 40.6 cm; the youngest specimen was also a female estimated at 1 year of age with a total length of 19.1 cm. The von Bertalanffy growth equation was estimated as L_t = 54.70 (1 ? exp (?0.37 (t + 0.21))). Concluded was that there is a significant relationship between body size, otolith dimensions and estimated age of Otolithes ruber.     

Biology of the kingsoldier bream (Argyrops spinifer, Forsskål 1775; Sparidae), from the Arabian Sea, Oman

It is recognized by the FAO that management of fish resources in the western Indian Ocean is complicated by the lack of data on the basic biology and landing statistics for exploited fish species. In this paper data are presented on the population biology of kingsoldier bream, Argyrops spinifer (Forsskål 1775), in the Arabian Sea with a view to contributing towards the development of management plans for its sustainable exploitation. Samples were obtained from the Omani artisanal hand‐line fishery catch, January 2001–December 2002. Total length (L_T) of fish sampled ranged from 20 to 68 cm (males) and 25 to 70 cm (females). The male : female ratio was similar up to 55 cm L_T but the larger size‐classes were composed predominately of male fish. L_T/carcass weight (W_C) relations for male and female fish were similar and the combined data produced an equation W_C = 0.00005 × L_T^2.67. Marginal increment analysis indicated an annual cycle of opaque and translucent ring formation in otoliths that was related to the change in surface water temperature during the annual monsoon period. The opaque zone was completed in May and the translucent zone began to form in June. Female and male fish age ranged between 2 and 25 years. Both males and females exhibited similar asymptotic growth patterns; the combined von Bertalanffy growth function was L_t = 64.6(1 ? e^{[?0.142(t + 0.489)]}). Gonadosomatic indices and gonad condition of male and female fish indicated that the spawning season occurred between September and January. Size (L₅₀) and age at first maturity (A₅₀) were estimated to be 36.5 cm L_T and 5.0 years for males and 37.2 cm L_T and 5.6 years females, respectively. The results of this study provide fundamental information on the biology and population dynamics of A. spinifer in the Arabian Sea that can be used in management models for the continued sustainable exploitation of this species in the Omani demersal coastal fisheries.     

Age and growth of Atlantic bluefin tuna, Thunnus thynnus (Osteichthyes: Thunnidae), in the Mediterranean Sea

The objective of the study was to describe the biometry of Mediterranean bluefin tuna, Thunnus thynnus, the biology of which is not yet well understood. A total of 504 specimens was collected from 1998 to 2005 in the central part of the Mediterranean basin. They were sexed and measured; fork lengths (FL) ranged from 51.0 to 255.0 cm while body weights (W) ranged from 2.6 to 247.0 kg. The first spiniform ray (spine) of the first dorsal fin was removed and cross‐sectioned near the condyle base in order to count annuli for age estimation. The regression coefficient (b) of the female FL–W relationship was significantly higher than that of the male, and both sexes displayed a negatively allometric growth (b < 3); male regression equation: ln W = ?2.942 + 2.730 ln FL; female regression equation: ln W = ?3.660 + 2.878 ln FL. Based on counts of the translucent zones in the sections of the first ray of the first dorsal fin, estimated ages ranged from 1 to 15 years for males and 1 to 14 years for females. The correlation between the spine ray (R) and FL fit the allometric model best; the R–FL regression equations of the two sexes did not differ significantly and the overall equation was: ln FL = 3.721 + 0.851 ln R. Due to the R–FL allometric correlation, estimates of fork lengths at previous ages, FL_i, were back‐calculated with a body proportional hypothesis. Von Bertalanffy growth equations were derived from both observed and back‐calculated FLs‐at‐age, which did not differ significantly. Moreover, no significant difference was found between the growth equations of the two sexes; the overall equation was FL_t = 373.08 [1?e^{?0.07(t + 1.76)}]. Weight‐at‐age values were derived from the von Bertalanffy predicted FLs‐at‐age by the FL–W correlation equations for males and females. The paper represents the first comprehensive study on the biometry, including age and growth, of bluefin tuna captured in the Mediterranean Sea.     

Reproductive biology of longnose trevally (Carangoides chrysophrys) in the Arabian Sea, Oman

The reproductive pattern of longnose trevally (Carangoides chrysophrys) in the Arabian Sea, off the coast of Oman, is described. Samples were collected on a monthly base between April 2005 and September 2006 from two landing sites (ALlakbi and Raysuot). A single peak of the gonadosomatic index (GSI) started from September and ended in February signalling the spawning period. Values of the relative condition factor (K _n ) were fairly constant throughout the year for both males and females and no significantly difference was found in the average K _n values between males and females during sampling period. Male and female lengths-at 50% maturity were 46.90 and 42.08 cm, respectively and were significantly different. This study thus increases our understanding of the reproductive biology of an important commercial and artisanal fish species in one of its major distribution areas.     

The use of sectioned otoliths to age barramundi (Lates calcarifer) (Bloch, 1790) [Centropomidae]

The relationship between the number of rings present in sagittal otoliths and the age of barramundi, Lates calcarifer (Bloch, 1790) [Centropomidae], was investigated by examining cross sectioned otoliths of 37 tagged fish of known age between 1 and 5 years from the Johnstone River, north Queensland. Concentric rings were clearly visible in all otolith sections and were validated as annual marks. The technique was then used to estimate the age and calculate von Bertalanffy growth parameters for 70 barramundi from the Fitzroy River, central Queensland. Growth appeared to be rapid but variable in the first year; the von Bertalanffy growth parameters for length versus age were L =690 mm, K=0.53, t ₀= 0.003 years. October 1 was designated as the birth date. Whole otolith length, width and thickness were also approximated well by the von Bertalanffy equation. We suggest that examination of otoliths is a useful technique for ageing barramundi but note that further validation of the ageing method is still needed for fish older than six years.