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Length–weight relationships (LWRs) were determined for three Carangid fish, [Alepes vari (Cuvier, 1833), Uraspis uraspis (Günther, 1860) and Carangiodes oblongus (Cuvier, 1833)] inhabiting in the Bay of Bengal coast, Bangladesh. A total of 147 individuals of three species were sampled from four different sampling points of the Bay of Bengal coast, Bangladesh and examined from April 2017 to October 2017. Fishermen operated beach seine nets (mesh size BSN, 30 mm) and drift gillnet (10.5 cm) twice in each sampling campaign to catch the studied species. The calculated value for parameter "b" of LWRs were 3.003, 2.945 and 2.980 for A. vari, U.uraspis and C. oblongus, respectively. [ABSTRACT FROM AUTHOR]

This study evaluates the catch rates, species composition and reproductive biology of flotsam-associated fishes targeted by ring nets off the southwest coast of Sri Lanka. Catch and number of multiday boats operating with ring nets were collected at Beruwala fishery harbor on the southwest coast of Sri Lanka, March to October 2013, by making fortnightly field visits. Fish samples were collected randomly from the unloaded ring net catches to analyze reproductive biology. Twelve fish species belonging to four major families: Scombridae, Carangidae, Coryphaenidae and Balistidae were identified in the ring net catches and five species, Decapterus russelli, Katsuwonus pelamis, Thunnus albacares, Elagatis bipinnulata and Canthidermis maculatus were predominant. An average of 25 ± 12% multiday boats landing at the Beruwala fishery harbor operated with ring nets each month, with an average monthly catch rate fluctuating from 730 ± 101 to 3924 ± 1094 kg per boat per trip. Catch rates of tunas and carangids were significantly higher than the other fish groups ( anova; d.f. = 3, P < 0.05). Total fish landed by ring nets at the Beruwala fishery harbor during the study period was 1456 tonnes. Species belonging to the family carangidae had the highest percentage contribution (46.6%) to the ring net landings followed by tuna (34%). Similar-size individuals ranging from 24 to 31 cm were landed by ring nets, with all landed individuals belonging to K. pelamis, T. albacares and E. bipinnulata having immature gonads. The findings of this study will be useful locally as well as regionally to manage the ring net fishery and to aid in implementing measures to manage the highly migratory tuna species. [ABSTRACT FROM AUTHOR]

Summary: Present study provides length–weight relationships (LWRs) and length–length relationships (LLRs) of eight fish species from river Ganga, India. Specimens were sampled from gill nets (mesh, 22–120 mm), cast nets (mesh, 12–14 mm), and seine nets (mesh, 12 mm) on quarterly basis from September 2016 to September 2017 within the river stretch from Buxar (25°33′43.90″N and 83°56′3.10″E) to Freserganj (21°35′40.58″N and 88°15′28.92″E). The b value ranged from 2.86 (Otolithoides pama) to 3.08 (Polynemus paradiseus), whereas a value ranged from 0.004 (P. paradiseus) to 0.016 (Rita rita). Both relationships (LWRs and LLRs) were found to be highly correlated (p < .001). This study provides first report on LWR for Amblyceps mangois and Osteobrama cotio, whereas new maximum length recorded for Macrognathus pancalus. Furthermore, the estimate of R. rita should be considered as tentative because of the limited size range in the study. [ABSTRACT FROM AUTHOR]

Multiple-pass (i.e. removal) sampling and mark-recapture experiments were undertaken in the Sydenham River ( Ontario, Canada) to assess the effectiveness of seining to detect and estimate the local abundance of blackstripe topminnow, Fundulus notatus (Rafinesque, 1820) as well as to compare catch characteristics from closed and open (with and without block nets) sample units. Probability of species detection using three-pass seining was estimated to be 0.58 in closed units, and 0.51 in open units. To be 95% confident of occupancy status, a minimum of five repeat surveys is required. A decline in catch occurred in only half of the sample units, population size estimates were often imprecise, and attempts to generate mark-recapture population estimates were unsuccessful. Mean capture probabilities were 0.48 in closed units and 0.65 in open units, when depletion occurred. For blackstripe topminnow and other fishes encountered, there were no significant differences between closed and open units in the frequency of depletion or capture probability. Compared to single-pass surveys, monitoring programs that employ three seine hauls are more likely to detect the presence of the blackstripe topminnow and any decline in local abundance. [ABSTRACT FROM AUTHOR]

An increase in yellowfin tuna ( Thunnus albacares) catch by danish seine fisheries around the subsurface fish aggregating devices ( FADs) in southern Taiwan waters has been a concern of local government and environmental groups. However, the attraction mechanism of aggregating tunas at the subsurface FADs is still poorly understood. The objective of this study is to examine the fine-scale vertical and horizontal movements of juvenile yellowfin tunas around a subsurface FAD. In total, 53 tunas (35-81 cm fork length) were tagged with ultrasonic telemetry tags and released at a subsurface FAD in the waters off Shiao-Liu-Chiu Island, southwestern Taiwan from October 2008 to December 2009. These tunas stayed at the subsurface FAD for up to 31 days, with daytime vertical movement depths averaging 60-80 m at a maximum depth of 250 m. At night, the tuna gathered at a shallow depth of 40 m. The mean depth of vertical movement in the daytime is significantly different from that of the nighttime (P < 0.05). The maximum detectable distance of horizontal movement was 1.6 km, with 80% of the long horizontal movements occurring in the daytime. It is likely that the purpose of these vertical and horizontal movements was for feeding or avoiding predators. Moreover, the tagged tunas did not depart from the subsurface FAD simultaneously, suggesting distinct behaviors in their movements. [ABSTRACT FROM AUTHOR]

The article offers information on tuna farming. It is stated that floating cages are located on the coasts of various Mediterranean countries, with small tunas provided mainly by the purse seine fishery to stock the cages. The study was promoted by the increase in off-shore farming activities and the use of technological systems to monitor aquaculture sites.

Lake sturgeon Acipenser fulvescens are imperiled throughout the Laurentian Great Lakes basin. Efforts to restore this species to former population levels have been ineffective due in part to limited information regarding its early life history. The objectives of this study were to characterize the larval drift and biological attributes of age-0 lake sturgeon in the lower Peshtigo River, Wisconsin. Lake sturgeon larvae were captured from May to June 2002 and 2003 using drift nets, while age-0 juveniles were captured from June through October 2002 and 2003 using wading, snorkeling, backpack electrofishing, and haul-seine surveys. Larval drift occurred within 14 days of adult spawning and extended from 1 to 3 weeks in duration, with two peaks in the number of fish drifting downstream each year. Larvae had a median total length (TL) of 19 mm (range: 13–23; N = 159) in 2002 and 18 mm (range: 13–24; N = 652) in 2003. Catch-per-unit-effort for larvae was 0.18 fish h−1 m2 and 0.94 fish h−1 m2 in 2002 and 2003, respectively. Age-0 juvenile lake sturgeon exhibited rapid growth (i.e. 2.57 mm day−1 in TL and 0.66 g day−1 in wet weight) throughout summer and fall months; relative condition of fish in both years was approximately 100, indicating good condition. Absolute abundance of age-0 juveniles in 2003 was estimated at 261 fish using the Schnabel estimator. The results from this study indicate that the lower Peshtigo River contains important nursery habitats suitable for age-0 lake sturgeon. [ABSTRACT FROM AUTHOR]

A total of 644 juvenile gilt sardine, Sardinella aurita Valenciennes 1847, were obtained by random sampling from the Zrmanja River estuary (Novigrad Sea Bay, eastern part of the North Adriatic), which is a nursery ground for small pelagic fish species. Gilt sardine were caught by purse seine as well as with beach seine. From their first recorded occurrence in this area, representative samples were collected monthly from October 2000 to May 2001. Monthly fluctuations in length frequency distributions of gilt sardine juveniles were observed. Total length was in the range of 8.0–16.0 cm. Minimum and maximum weights recorded were 3.02 g and 28.98 g respectively. The modal number of vertebrae was 47, with a mean of 47.13 vertebrae. Length–weight relationship of the gilt sardine juveniles was described by the expression: W = 0.0043 L3.1162. [ABSTRACT FROM AUTHOR]

The catches and discards of trawlers, seiners and trammel netters were studied in the Algarve (southern Portugal) using observers onboard commercial fishing vessels. Species diversity was high, with 236 species recorded as occasionally, frequently or regularly discarded. Mean discard rates per trip were 0.13, 0.20, 0.27, 0.62 and 0.70, respectively, for trammel nets, demersal purse seines, pelagic purse seines, fish trawls and crustacean trawls, with high variability in terms of discard volume and discard rate. This was especially so for seiners where from 0 to 100% of the total catch might be discarded. No significant relationships were found between discard quantity or discard rate and characteristics of the fishing vessels sampled within each métier (total length, TAB, hp, kW). Based on the above discard rates and the official landings, it was estimated that in 1996, Algarve trawlers discarded 9000–13000 tonnes (t) while seiners discarded 5500–8200 t. Discarding practices in these fisheries are reviewed and the reasons for discarding are presented by species and métier basis. The results support the need for more studies on the factors contributing to discarding, variability in discard quantities and rates, the fate of discards and their importance to the marine ecosystem, and on ways of reducing by-catch and discarding in these fisheries. [ABSTRACT FROM AUTHOR]

Weight–length relationships (WLR) are presented for 50 fish species from the seagrass beds of Guadeloupe and Martinique. Samples were taken in shallow waters (<2 m) with different types of fishing gear: seine net, hoop net and gill net. The b coefficient in the WLR varied between 2.63 and 3.61 and showed a mean value of 3.07 (SE = ± 0.06). [ABSTRACT FROM AUTHOR]