Taking full advantage of the diverse assemblage of data at hand to produce time series of abundance. A case study on Atlantic salmon populations of Brittany

Estimation of abundance with wide spatio-temporal coverage is essential to the assessment and management of wild populations. But, in many cases, data available to estimate abundance time series have diverse forms, variable quality over space and time and they stem from multiple data collection procedures. We developed a Hierarchical Bayesian Modelling (HBM) approach that take full advantage of the diverse assemblage of data at hand to estimate homogeneous time series of abundances irrespective of the data collection procedure. We apply our approach to the estimation of adult abundances of 18 Atlantic salmon populations of Brittany (France) from 1987 to 2017 using catch statistics, environmental covariates and fishing effort. Additional data of total or partial abundance collected in 4 closely monitored populations are also integrated into the analysis. The HBM framework allows the transfer of information from the closely monitored populations to the others. Our results reveal no clear trend in the abundance of adult returns in Brittany over the period studied.

STRUCTURE AND DYNAMICS OF CATCHES OF THE SHURYSHKARSKY DISTRICT OF THE YAMALO-NENETS AUTONOMOUS OKRUG

Анализ статистики уловов Шурышкарского района показал, что в 2015-2020 гг. промысловое значение имели 12 видов рыб, обеспечивая уловы от 8,6 до 10,1 тыс. тонн. Наибольший вклад в уловы по району вносили щука (47 %) и язь (27 %), доля сиговых в этот период снизилась с 22 до 11 %. Доля района в освоении биоресурсов ЯНАО возросла с 13 до 23 %, вклад в общие уловы щуки, леща, язя, окуня и карася в отдельные годы превышал 30 %. The analysis of catch statistics of the Shuryshkarsky district showed that in 2015-2020, 12 fish species were of commercial importance, providing catches from 8.6 to 10.1 thousand tons. The largest contribution to catches in the region was made by pike (47 %) and ide (27 %), the share of whitefish in this period decreased from 22 to 11 %. The share of the district in the development of biological resources of the Yamalo-Nenets Autonomous District increased from 13 to 23 %, the contribution to the total catches of pike, bream, ide, perch and crucian in some years exceeded 30 %.

Experience of the monitoring of the littoral fish assemblages at reserved waters (on the example of the Karadag Nature Reserve aquatory, Crimea)

Feasibility of monitoring of the littoral fish assemblages at the reserved water areas (Karadag Nature Reserve, Crimea) by methods of visual estimation and video recording involving data of fish catch statistics of fishing companies and recreational fishermen providing fishing in the waters adjacent to the reserved aquatory is discussed. At the water area of the reserve 18 species (35%) were identified exclusively by visual recording and video recording methods, 13 more species were identified by the mentioned contactless methods and simultaneously as a result of the analysis of information from recreational fishermen and fish catch statistics. As a result, 31 species of fish (or 61 % of the identified species) were identified visually or by video recording. The contactless methods were detected mostly sedentary (15) and nomad (11) species. Migratory species in the majority (9 species vs. 6) were identified only as a result of the analysis of information from recreational fishermen and fish catch statistics.

An optimized catch-only assessment method for data poor fisheries

Catch statistics are perhaps the most commonly collected data and are widely available for many fisheries. However, it is currently difficult to provide scientific advice for management purposes using only catch data. This article presents a catch-only method for stock assessment of data-poor fisheries. It uses time series of catches and two priors, one for the intrinsic population growth rate derived from life history parameters, and another for stock depletion based on catch trends. The method applies an optimization algorithm to search the potential parameter space. All computations are model or equation based rather than using predefined rules. The utility of this method is demonstrated by applying it to 13 stocks in Australia that are assessed using Stock Synthesis—an assessment package that can make use of a variety of data sources. The estimated parameters, including carrying capacity, intrinsic population growth rate, maximum sustainable yield, and depletion from the catch-only method are broadly comparable with those from the full assessments. The circumstances in which the method may perform poorly, such as longer-term changes in productivity and episodic recruitment, are highlighted.

Stowaways in the catch: Identification of Xenobrama microlepis in the haul fishery for Brama australis

Species that occur in low abundances and that are morphologically similar to the target fish are often undetectable in fisheries hauls; however, they add to the catch statistics of the target species. Using mitochondrial DNA and phylogenetic approaches we identified 6 individuals of the species Xenobrama microlepis in a haul targeting the southern Ray’s bream (Brama australis) taken by artisanal fishermen close to Chilean coast. The presence of X. microlepis increases the regional marine biodiversity of fishes in Chilean waters, and fisheries managers should pay attention to the hidden biodiversity in the fishery statistics.

SOUTHERN BLUEFIN TUNA IN THE INDONESIAN LONGLINE FISHERY: HISTORICAL DEVELOPMENT, SEASON, SOME BIOLOGICAL PARAMETERS; LANDING ESTIMATION AND CATCH STATISTICS FOR 1993

The longline fishery based in Beli her expended rapidly in rcccnt ycrrs: 291 vcarcls,mdnly of reiwancsc origin, operatcd out of Benor in 1993.

Stretching the truth: length data highlight falsification of Japanese sperm whale catch statistics in the Southern Hemisphere

Falsification of reports on Japanese catches of sperm whales ( Physeter macrocephalus ) is known to have occurred at both land whaling stations and in North Pacific factory fleets. Here, we conduct an analysis of pelagic sperm whale catches in the Southern Hemisphere: we compare true Soviet length data from the Yuri Dolgorukiy factory fleet during 1960–1975 to data for the same period reported to the International Whaling Commission (IWC) by Japan. Prior to implementation of the International Observer Scheme (IOS) in 1972, the Soviet fleet killed 5536 females, of which only 153 (2.8%) were at or above the minimum legal length of 11.6 m. During the same period, Japan killed 5799 females and reported that 5686 (98.5%) were of legal size, with 88.5% of the entire length distribution reported as being between 11.6 and 12.0 m. This unrealistic distribution, together with the fact that Japanese fleets were supposedly able to catch 37 times the number of legal-sized females as the Soviet fleet, indicates extensive falsification of catch data by Japan. Further evidence of misreporting is that females >11.5 m dropped to 9.1% of the Japanese catch after 1971, when the IOS made cheating much more difficult. That 99.6% of 10 433 males in the pre-IOS catch were also reported to be of legal size, indicates that illegal catches were not confined to females. We caution that the Japanese sperm whale data in the IWC Catch Database are unreliable and should not be used in population assessments. The ease with which illegal catches were apparently made underscores the past failures of the IWC to effectively regulate whaling.

CURRENT STATUS AND PROBLEMS OF THE CATCH STATISTICS ON ANGUILLID EEL FISHERY IN INDONESIA

To compensate the decline of the populations of temperate anguillid eels, tropical anguillid eels become getting attention of East Asian eel market in recent years. Many eel farms have been established in Java Island to culture tropical anguillid eels intending to export the products to East Asia. Since eel farming is reliant on wild-caught anguillid eels such as glass eels, elvers and yellow eels, these eel seeds have been captured in various places in Indonesia. However, it is still unknown that how much of tropical anguillid eels are caught as seeds for eel farming. This study showed two different patterns of the commodity chains of eel seeds from both Sukabumi Regency and Bengkulu Province to the eel farms in Java Island. Official catch statistics on anguillid eels found in both Sukabumi Regency and Bengkulu Province were also analyzed on their features and problems underlied. Considering the sustainable use of anguillid eel resources and critical stances on exploitation of eel seeds from all over the world, the Indonesian government should take an immediate action for developing the national catch statistics on anguillid eel fishery as soon as possible.