A total of 558 specimens of black-bellied anglerfish Lophius budegassa (Spinola, 1807) were collected by the vessels engaged in commercial trawl fishing in the Central Aegean Sea between September 2017 and August 2018 in order to determine age and growth. Ageing was based on growth ring counts of transverse sections of the illicium (first ray of the dorsal fin). By reading the illicium, individuals were found within II-XI age groups. Total lengths and weights ranged between 12.0 – 65.0 cm and 24.5 – 4682.0 g, respectively. Von Bertalanffy growth parameters were estimated for males, females and combined sexes of L. budegassa. The results are compared with previous studies.
There is a significant lack of data for the biological parameters of beluga or great sturgeon, the largest fish in the Caspian Sea. The age, growth and fisheries indices for the stock status of beluga was investigated in the south Caspian Basin of Iran between 1990 and 2011. Fork lengths ranged between 113-420 cm and weights from 8.0 to 725.0 kg. The growth parameters were L∞ = 440 cm, K = 0.027 year−1, t0 = − 5.8 years. The age at first capture (tc) was 13.1 years. The long-term age composition data showed age up to 63 years, and the ages 12-19 years comprised 76.7% of the total catch. The generation length was 33 years. The values of “KF” were close to 1 or >1, indicating that beluga sturgeon is in a favorable condition in the southern Caspian Sea. The length distribution showed that 24.2% of the catch is comprised of juveniles. Based on the age structure and age at first maturity, recruitment and growth overfishing occurred in beluga stocks. Therefore, increased length or age at first capture in future fishery policies should be implemented. The mega-spawners represented 4.4% of the fish captured and revealed an unhealthy population structure.
This study investigated the efficacy of Tamarind Leaves (TL) and Mango Leaves (ML) with Oxytetracycline (OXY) on growth performance, haematoimmunological and disease resistance of Clarias gariepinus juveniles against Aeromonas hydrophila. Experimental diets consist of control (0%), TL2 (1%), TL3 (2%), ML4 (1%), ML5 (2%), OXY6 (30mg/kg diet), (TL+ML) 7, (TL+OXY) 8, (ML+OXY) 9 and (TL+ML+OXY) 10. The fish (3.02±0.01g) were replicated twice with 20 fish per replicate and were fed twice daily at 3% body weight of 40% crude protein for twelve weeks (8 weeks for feeding trial and 4 weeks for challenge test). Mean Weight Gain (MWG), Specific Growth Rate (SGR), Packed Cell Volume (PCV), Haemoglobin (Hb), Lymphocytes (LYM), Globulin (GLO), Amino Alanine Transferase (ALT) and Aspertate Amino Transferase (AST) contents were ascertained using standard technique. The fish were infected with A. hydrophila at 5.94 log10 CFU/ml interperitoneally and fed different diets to evaluate their Relative Percent of Survival (RPS). Data was subjected to descriptive statistics and one-way analysis of variance at P=0.05. Clarias gariepinus juveniles fed treated diets had higher growth rates than the control diet but C. gariepinus fed (TL+ML+OXY) 10 had a significantly higher MWG and SGR of 7.74±0.69 g and 0.97±0.01 g, respectively. The PCV (44.0±2.00%), Hb (14.7±2.00 g/dl), LYM (37.0±2.00), GLO (42.0 ±2.00 g/dl) were higher in the C. gariepinus fed (TL+ML+OXY) 10 than the control diet. The AST and ALT values among the treated groups were lower than the values in the control at the post-challenge test. The RPS against A. hydrophila was higher in the treated groups (100%) than in the control (0%). Fish fed tamarind and mango leaves had enhanced mean weight gain and were more resistant to A. hydrophila infection.
Loss of fish biodiversity, especially in the inland and coastal areas, is a major concern in sustainable fish production. Indiscriminate fish catch, climate change and many other anthropogenic activities synergistically affect fish biodiversity. To formulate a sustainable fish biodiversity conservation plan, fish biodiversity in the Andharmanik River, a 40-km-long Hilsa shad sanctuary in the southern part of Bangladesh, was assessed. The study was conducted to understand the status of fish species diversity through sampling in three sampling stations between December 2014 and November 2015. A total of 93 fish species were found belonging to 66 genera, 45 families and 14 orders. Perciformes (27.65%) was found to be the most dominant order, followed by Cypriniformes (20.21%), Siluriformes (21.28%) Clupeiformes (7.45%) Mastacembeliformes (4.26%) and Channiformes (4.26%). Out of the 93 fish species of the river, the percentage compositions of the vulnerable, endangered, critically endangered and not threatened were found to be 14%, 11%, 6% and 59%, respectively. Four population indices viz. Shannon-Wiener’s diversity index (H), Simpson’s dominance index (D), Simpson’s index of diversity (1-D) and Margalef’s index (d) were applied to demonstrate species diversity, richness and evenness of fish species in sampling areas, and the overall values of the indices were 2.70-3.51, 0.10-0.12, 0.88-0.90 and 7.84-8.19, respectively. The main threats to fish biodiversity were reviewed and the measures for fish biodiversity conservation of the river recommended. Indiscriminate fishing using biodiversity destructive gears, as well as losing hydrological and ecological connectivity with the surrounding habitats, were identified as major threats to biodiversity in the Andharmanik River. Effective sanctuary-based co-management, immediate actions for habitat enhancement to conserve and improve fish biodiversity in the river were recommended. Necessary steps to improve hydrological and ecological connectivity for habitat protection and elimination of all destructive fishing gears in order to conserve biodiversity in the Andharmanik River were also suggested.
The aim of this paper is to provide an overview of bluefin tuna, with special regard to its farming challenges. Tuna is one of the most prominent species in fisheries worldwide. The high market value of tuna stocks has led to intensified fishing pressure that resulted in drastic population reductions in every ocean where these fish are found. It is very difficult to obtain the necessary data for the appropriate stock assessment analysis, and there is a very high degree of uncertainty in the models used to evaluate Atlantic bluefin tuna stocks. Tuna-farming could help reduce pressure on the tuna population, but the problem is that the majority of cage-farmed fish is caught in its natural environment (wild population), and thus is fattened or farmed to a certain size. Additionally, the challenges in tuna farming are numerous. Tuna is a fast swimmer, a large energy and oxygen consumer, therefore consuming a large portion of available food to maintain its metabolism. However, due to its delicious taste, high market price and a large demand for this species, pressure will probably continue to grow in the future. Therefore intensive farming, which implies the full breeding cycle in captivity, remains one of the possible solutions that could help reduce the pressure on the tuna population.
Nuclear Expressed Sequence Tag (EST) microsatellite markers were developed for the Tasmanian palaeoendemic conifer Lagarostrobos franklinii (Hook.-f.) Quinn for genetic studies. RNAseq data was mined for EST microsatellites, and primer pairs were synthesised from 70 contigs with 50 producing amplification products. Of these 50, 10 reliably amplified and displayed polymorphism across 8 samples representing the entire species range. The genetic diversity of these 10 loci was then examined in three wild populations (84 samples). The number of alleles varied from two to thirteen per locus with the average number of alleles per population ranging between 3.0 – 4.7. Observed and expected heterozygosity ranged from 0.34 – 0.42 and 0.37 – 0.44, respectively. Marker cross-amplification was tested in the New Zealand sister species Manoao colensoi (Hook. f.) Molloy, but no markers amplified reliably, which possibly reflects the age of divergence between these species (~64 million years). These are the first microsatellite markers developed for the monotypic genus Lagarostrobos. They will be valuable for assessing the species extant genetic diversity, the impact of past climatic perturbations and human disturbance and the role of clonal propagation in recruitment.
Forest companies prefer a coppice system as a silvicultural strategy owing to its economic and sustainability advantages compared to developing new plantations for second rotations. However, studies aiming to determine the selection of superior genetic material for this management strategy are scarce. In this study, we evaluated five clonal tests of Eucalyptus spp. located in Itatinga and Angatuba, São Paulo State, Brazil, to determine the genetic correlations and control of productivity for regrowth management in two rotations. The volume (m3) and survival of the Eucalyptus spp. clonal tests were determined for the two rotations at 5.5 years of age. The experiments were carried out in a randomized block design with six replicates, five plants per plot, and unbalanced treatments. The heritability in the normal scale () for the survival ranged from 0.056 to 0.11, the heritability in the broad sense () ranged from 0.205 to 0.334, and the genotypic correlation was positive and high (0.71-0.86), and statistically significant to the genetic means for the two rotations. The ranking of the best clones in the second rotation was similar (76 %) to their ranking in the first selection. Thus, for the evaluated material, there was no need for the second measurement to obtain accurate selection when managing a coppice system.
This study examined and described the basic parameters of the catch-and-release angling of roach Rutilus rutilus and European perch Perca fluviatilis with the mormyshka technique. Catch efficiency, the size of the fish caught, the time required to unhook the fish and the total time during which the fish were handled, hooking location, the occurrence of injury and initial hooking mortality were determined. The study indicates that the mormyshka technique is an effective way to catch roach and European perch when ice fishing. The efficiency of the catches and landings was similar for barbed and barbless hooks. The mormyshka technique also proved to be safe for the fish during catch-and-release fishing. The decided majority of fish were hooked shallowly on the upper jaw, which is a safe location, and injury occurred rarely regardless of the hook type. Generally unhooking the fish from the mormyshka hook was seamless and fish handling was brief. Additionally, when roach were caught with barbless hooks, unhooking time and handling was shorter than it was with barbed hooks. No initial hooking mortality was observed in roach, while it occurred in only two specimens of European perch.
Cooperative-based growth model for agricultural enterprises is gradually gaining popularity in application. This study examined the effect of cooperative financial intervention on the growth of catfish aquaculture value chain in Nigeria. Primary data collected, with well-structured questionnaire from 120 participants in aquaculture value chain, were analyzed with descriptive statistical tools, cost and return function and 4-point likert-type scale. The result shows that 32.3% and 27.3% of processors and input suppliers accessed N320,000 and N270,000, respectively. Only 18.2% of producers accessed N180,000. The result indicates that there are more catfish producers than any other operators in the value chain. There is interdependence between catfish producers and input suppliers, processors and marketers in the value chain. Furthermore, catfish processors and inputs suppliers accessed more cooperative loan because their activities were capital intensive. The relatively high amount of cooperative fund accessed by these groups translated high growth rate of 55% and 53%, respectively. The major constraints to the growth of catfish value chain were inadequate credit access and high expenditure on inputs. Operators in the catfish aquaculture value chain should be encouraged to attend workshops on management techniques to improve the efficiency of their businesses.
Harry hotlips (Plectorhinchus gibbosus), belonging to the fish family Haeumulidae, is recorded for the first time off the Iranian coast of the Oman Sea, Chabahar Bay (25°18′N, 60°37′E). Identification confirmed by comparing morphological data of the collected specimen with data of reported congener species off this area.