New estimates and complications in the assessment of female functional maturity for the European lobster (Homarus gammarus) on the Yorkshire Coast (UK)

New estimates of female Homarus gammarus functional maturity were developed from targeted offshore and quayside based industry surveys in the Yorkshire Coast fishery. Offshore surveys also provided the first stock specific quantification of pre-recruit contributions. A contrast in results identified a new complication in estimating functional maturity attributed to ‘soft’ animal exploitation which is reviewed and assessed.

Inclusion of cricket (Gryllus bimaculatus) meal in African catfish (Clarias gariepinus) feed influences disease resistance

In our present study, we observed the effect of cricket meal (CM) on disease resistance of African catfish. Fish were fed diets containing 350 g kg–1 and 400 g kg–1 of CM and 350 g kg–1 of fishmeal as control. The fish were divided into triplicates treatments of ten fish per replicate, weighed 22.5±0.6 g and fed with experimental diets for 40 days before being challenged against Aeromonas hydrophila. Relative percentage of survival (RPS) was recorded over 12 days post-challenge. White blood cell count, total protein, globulin and lysozyme showed significantly increasing levels in those fed with cricket meal diet compared to the control group. Mortalities at 12-day post-challenge significantly decreased to 30% (RPS: 66.7%) and 27% (RPS: 70%) for 35% and 40% CM respectively compared to 90% mortality in control group. Intestines and liver tissues of infected fish were dissected for pathogenic confirmation. The intestines of control diet showed the highest bacterial load (58.2×107 cfu g–1) compared to CM diets. The current study indicates that dietary CM could enhance the innate immune system and disease resistance of African catfish.

First record of Trypauchen vagina (Bloch and Schneider 1801) (Perciformes: Gobiidae) in the Narmada River, Gujarat, India

Gobiids are a large group of fishes inhabiting freshwater, marine and brackish water habitats. Trypauchen is the Indo-Pacific genus and comprises of two species: Trypauchen pelaeos known from Myanmar, Malaysia, Thailand, Vietnam and China; and T. vagina, distributed from Kuwait, along the coasts of India, ranging eastward to the Philippines, Taiwan and China. A specimen of T. vagina (Bloch and Schneider 1801) was caught by cast net from the shallow water of the Narmada River on 11 April 2017 that has later been preserved in the museum of Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara (voucher number: ZL-CH-OSH-026). This paper presents the first observation of T. vagina in the Narmada River in Gujarat.

Freshwater fishes of Orissa, India

Varied freshwater resources of Orissa blessed with diverse fish fauna. In total, 186 species of fishes belonging to 11 orders, 33 families and 96 genera were recorded from various freshwater bodies of Orissa. Cypriniformes was the most dominant order and Cyprinidae was diverse family. The trophic level of fishes of Orissa ranged from 2.0 to 4.5 containing 62.41% of carnivorous species. Fishery status revealed existence of 120 species worth for capture fishery, 101 species worth for ornamental fishery, 37 species worth for culture fishery and 25 species worth for sport fishery. Threat status comprises of one Critically Endangered species, five Endangered species, three Vulnerable species and remaining 177 species were Not Threatened. The findings of present communication may serve as baseline information for planning, conservation and management of fish and fisheries resources of Orissa.

African catfish Clarias gariepinus farming practices in North and South 24 Parganas districts of West Bengal, India

Clarias gariepinus is widely cultured due to its tolerance to environmental extremes, high production and good feed conversion rate. This communication describes the farming practices of C. gariepinus in North and South 24 Parganas districts of West Bengal. Clarias gariepinus is cultured in ponds of 0.1–0.75 ha, where fingerlings were stocked at a density of 860–1150 cubic meter–1. The current practices of seed transportation were stressful to fish as the majority of the farmers noticed 5–10% mortalities, despite the use of antibiotics. Acclimatization of seeds was practiced by the majority of farmers before stocking. Different feeds including slaughter-house wastes and dead poultry were supplied. Multiple stocking and harvesting were a common practice. Major problems identified were insufficient feed, disease, transport, poor seed quality and lack of financial support. The survival percentage was poor, as 88% of the farmers recorded <40–50% survival at harvest. Dropsy was the most common disease and had a significant impact on economy. Antibiotics or other aquadrugs were frequently used for treatment, although the success varied. In general, the C. gariepinus farming has helped to recycle the wastes generated in and around metropolitan Kolkata and adjacent municipalities into wealth, but it suffers from management issues and huge economic losses. This calls for immediate attention from researchers, administrators and extension personals.

Evaluation of some edible leaves as potential feed ingredients in aquatic animal nutrition and health

In this study, the potential benefits of ten edible leaves (Manihot esculents, cassava leaf; Colocasia esculenta, cocoyam leaf; Talinum triagulare, water leaf; Telfairia occidentalis, fluted pumpkin leaf; Carica papaya, pawpaw leaf; Amaranthus chlorostachys, green leaf; Moringa oleifare, drumstick leaf; Vernonia amygdalina, bitter leaf; Ipomoea batatas, sweet potato leaf and Basella alba, Malabar spinach ‘Amunututu’ to aquatic animal nutrition and health were studied along with proximate, mineral and phytochemical compositions. Results show that theses edible leaves were a good source of protein and the highest crude protein was obtained in C. papaya (32.6%) while the lowest in C. esculenta (14.7%). The highest and lowest total ash was found in T. triagulare (34.6%) and C. papaya (11%) respectively. The result showed that the edible leaves are rich in wide variety of secondary metabolites of phytochemical constituents such as tannins, alkaloids, flavonoids, saponins, glycosides oxalates and phytate which can act against different diseases. Results suggest that inclusion of edible leaves may be nutritionally beneficial and this could promote growth, immune system and enhance disease resistance properties and subsequently very potential to reduce the cost of highly priced supplementary feeds.

Impacts of water regulation on Tenualosa ilisha in the Narmada Estuary, Gujarat, India

Hilsa, Tenualosa ilisha is a highly prestigious fish for esteemed delicious taste, high market demand and price. It forms an important fishery of funnel-shaped 72 km long Narmada Estuary. Rapid decline in hilsa catch has been recorded in the Narmada Estuary over last few decades. Hilsa catch was recorded 5180 ton in 2006–07 that reduced to only 419 ton in 2014–15. Pre-impoundment of dam showed that T. ilisha contributed to the tune of 977.1 to 3727 ton from 1974–75 to 1982–83 and the highest catch of hilsa was 15319 ton during 1993–94. Sardar Sarovar Dam started functional in the year 1994 which has impacted natural water flow of the river and resulted in a reduction of freshwater availability in the estuary; the development of sand bars at the mouth of the estuary also reduced the tidal ingress into the system; low depth, loss of breeding, nursery and feeding grounds, over fishing may be the most important factors affecting hilsa fishery in Narmada estuary. Catching of juvenile hilsa during winter by ‘Golava’ net (small meshed bag net) also led to a rapid decline in hilsa catch. To maintain the sustainable yield of hilsa, selective fishing and control of juvenile catch are the prerequisites along with maintaining regular flow from the dam.

Growth performance, haematology and histopathology of African catfish (Clarias gariepinus) fed varying levels of Aloe barbadensis leaves

One hundred and twenty Clarias gariepinus fingerlings (2.33 ± 0.07 g) were fed with 40% crude protein diets containing three concentrations of Aloe barbadensis leaves-paste: ABL1, 1%; ABL2, 2%; ABL3, 3%, and control, 0% ad libitum twice daily for 12 weeks. Mean weight gain and percentage weight gain increased (P < 0.05) as concentration of A. barbadensis increased. Survival rate decreased as concentration of paste increased. Differences (P < 0.05) seen in packed cell volume (PCV), haemoglobin (Hb), and red blood cell (RBC), thus highest in ABL3: PCV (36.67 ± 0.89%), Hb (12.37 ± 0.37 g dl–1) and RBC (3.47 ± 0.08×106 L–1) and lowest in control: PCV (22.0 ± 0.58%), Hb (7.37 ± 0.20 g dl–1) and RBC (2.07 ± 0.06 ×106 L–1). Liver histology of control fish was normal, while fatty degenerations were seen in the treated fish. The histology of fish kidney was normal in all treatments. The study concluded that 1% A. barbadensis leaves-paste could effectively improve growth performance, nutrient utilization and survival of cultured C. gariepinus.

Toxic effect of lead on the fingerlings of Cirrhinus mrigala (Hamilton, 1822)

Pollution of water bodies caused by heavy metals such as lead is a major problem affecting aquatic fauna. The effect of lead on the fingerlings of fishes has not been widely investigated. The present study was undertaken to evaluate the impact of heavy metal lead on the fingerlings of the freshwater fish, Cirrhinus mrigala. Different concentrations of lead nitrate solutions, viz., 1 ppm, 10 ppm, 40 ppm, 100 ppm, 120 ppm, 160 ppm, 200 ppm, 240 ppm, 300 ppm, 400 ppm and 500 ppm were prepared. Ten fingerlings were introduced into each concentration. The mortality rate and the time of survival of fingerlings in the lead nitrate solution during next 96 hours were recorded. The mortality rate increased to a sudden plateau from 100 ppm to 200 ppm (from 10% to 100%) and total mortality was attained at 200 ppm. LC50 for the fingerlings was found to be 160 ppm. There was almost instantaneous mortality – absolute intolerance – of the fingerlings at 500 ppm. Our study results show that the fingerlings of Cirrhinus mrigala can survive the toxic effect of lead nitrate up to 40 ppm, without physiological stress.

Production and economics of carp polyculture in ponds stocked with wild and hatchery produced seeds

Lack of quality carp seeds is one of the major problems for fish production in Bangladesh. This experiment was conducted during July to December 2013 to study the production and economics of carp polyculture using wild and hatchery produced seeds in ponds in Faridpur district, Bangladesh. Seeds of native major carps (NMCs) (Catla catla, Labeo rohita and Cirrhinus mrigala) and non-native carps (NNCs) (Hypophthalmichthys molitrix, Ctenophryngodon idella, Aristichthys nobilis and Cyprinus carpio) from four different sources were tested in feed and fertilizer based polyculture ponds under controlled mesocosm trials with four treatments (T1–T4), each with four replications. Combination, weight and density of the stocked species were same for all the treatments. Water quality parameters were monitored monthly and mean values were found within suitable range for fish farming. Mean final weight, weight gain, specific growth rate and yield of L. rohita, C. catla and C. mrigala were found significantly (P < 0.05) higher with treatment T1, T3 and T2 respectively. Treatments T1, T2 and T3 varied more significantly (P < 0.05) than treatment T4 for total fish yield and cost benefit ratio. Polyculture of wild sourced NMCs and hatchery produced NNCs were found more profitable than aquaculture of hatchery produced NMCs and NNCs.