Atlantic mackerel and horse mackerel egg survey: Dutch participation May and June 2010

Every three years an international Atlantic survey is carried out by different European institutes to monitor the spatial and seasonal distribution of Atlantic mackerel and horse mackerel. During this survey mackerel and horse mackerel eggs are sampled using a plankton torpedo or bongo nets. The survey covers the whole spawning area and season. It starts along the Portuguese coast in February and continues until July when the waters west of Scotland are sampled. The mackerel and horse mackerel egg survey is coordinated by the ICES working group for mackerel and horse mackerel egg surveys (WGMEGS). England and France started the egg survey in the western area in 1977. The Netherlands participates since 1983. Nowadays participating countries and sampling area have expanded. In 2010 the following countries participated in this survey: Faeröer Islands, Germany, Iceland, Ireland, Norway, Portugal, Scotland, Spain and The Netherlands

Status of the Jack Mackerel resource and its management

The jack mackerel, Trachurus symmetricus, resource off the west coast of North America is known to be large and widely distributed. The spawning biomass is estimated to be 2.1 to 4.8 million tons based upon abundance of jack mackerel eggs collected at sea. The distribution extends from the Gulf of Alaska to the Gulf of Tehuantepec, off the coast of southern Mexico, and as far as 1,500 miles seaward. Within this range lies an area of maximum density which extends from Point Conception to central Baja California. Jack mackerel biological data has not been processed very rapidly due to higher priorities for analysis of sardine and Pacific mackerel data, and the apparent healthy condition of this resource. The California Department of Fish and Game initiated several projects in 1972 to resolve unanswered biological questions. (14pp.

Report of the Horse Mackerel Exchange and Workshop 2006

Following a recommendation from PGCCDBS, a workshop on age calibration of horse mackerel was carried out. The workshop was preceded by an exchange. The objectives were: to improve the quality of horse mackerel readings by international calibration. In particular, attempt to resolve the observed differences between countries. Estimate the accuracy and precision of the age readings before and after the intercalibration. Take into account differences between areas and methods. Training of new horse mackerel readers

Socioeconomic characteristics of payang seine (lampara) and driftnet fisheries in West Sumatra, Indonesia

A proportionate random sample survey of 10 percent of the driftnet and Payang seine fishers in West Sumatra was carried out in 1998. A total of 45 driftnet and 66 lampara fishers were interviewed to obtain socioeconomic data on the fisheries. About 40 percent of the driftnet and 76 percent of the lampara fishers owned and operated their fishing vessels and gears indicating a high level of ownership of fishing assets by these small scale fishers. The lampara catches consisted mainly of eastern little tuna, skipjack tuna, yellow fin tuna and mackerel, while the driftnets caught mainly Spanish mackerel, Indian mackerel, eastern little tuna and scad

Results of Jack Mackerel tagging study, 1971-75

Methods and materials used to tag and recapture jack mackerel, Trachurus symmetricus, off the coast of southern Ca1ifornia and Baja California, Mexico, are described. Tagging, recapture, and movement data resulting from this program are reported. Analysis of these data indicates substantial movement of jack mackerel within the range of the California fishery and suggests a seasonal inshore-offshore movement pattern. (13pp.

Horizontal distribution and overlap of planktivorous fish stocks in the Norwegian Sea during summers 1995–2006

The Norwegian Sea harbours several large pelagic fish stocks, which use the area for feeding during the summer. The period 1995–2006 had some of the highest biomass of pelagic fish feeding in the Norwegian Sea on record. Here we address the horizontal distribution and overlap between herring, blue whiting and mackerel in this period during the summers using a combination of acoustic, trawl and LIDAR data. A newly developed temperature atlas for the Norwegian Sea is used to present the horizontal fish distributions in relation to temperature. The centre of gravity of the herring distribution changed markedly several times during the investigated period. Blue whiting feeding habitat expanded in a northwestern direction until 2003, corresponding with an increase in abundance. Strong year classes of mackerel in 2001 and 2002 and increasing temperatures throughout the period resulted in an increased amount of mackerel in the Norwegian Sea. Mackerel was generally found in waters warmer than 8°C, while herring and blue whiting were mainly found in water masses between 2 and 8°C. The horizontal overlap between herring and mackerel was low, while blue whiting had a large horizontal overlap with both herring and mackerel. The changes in horizontal distribution and overlap between the species are explained by increasing stock sizes, increasing water temperature and spatially changing zooplankton densities in the Norwegian Sea

Description of embryonic development of Atka mackerel (Pleurogrammus monopterygius)

Atka mackerel (Pleurogrammus monopterygius) is hexagrammid fish that inhabits the temperate and subarctic North Pacific Ocean and neighboring seas (Fig. 1). This highly abundant fish is a critically important prey species (Sinclair and Zeppelin, 2002; Zenger, 2004) that supports a directed commercial trawl fishery (Lowe et al., 2006). Atka mackerel is a demersal spawner and males provide parental care to eggs (Zolotov, 1993). During breeding periods, sexually mature males aggregate on the bottom at nesting sites where they establish territories (Lauth et al., in press). Sexually mature females periodically visit male nesting territories from July to October to spawn batches of demersal egg masses (McDermott and Lowe, 1997; McDermott et al., 2007). Individual nests may consist of multiple egg masses deposited by different females, and males defend nesting territories for a protracted period lasting from the time territories are being established until all eggs within the territory are completely hatched (Lauth et al., 2007). Knowledge about the timing of the reproductive cycle and the use of spawning habitat are important for understanding population structure and the dynamics of stock recruitment, which in turn are important factors in the management of Atka mackerel populations

Status of Pacific Mackerel spawning population, 1973

This is the first annual report of the status of the spawning population of the Pacific mackerel as required by Section 8388.3 of the Fish and Game Code. During 1972 and early 1973, several methods of determining population size were investigated as mechanisms for estimating the spawning population size of Pacific mackerel stocks north of Punta Eugenia, Baja California, and a method using tagging procedures proved to be the most acceptable. The estimate of the Pacific mackerel spawning population obtained by tagging procedures was 5,480 tons. This estimate agrees generally with those obtained from alternate methods in which previously computed spawning biomass estimates were correlated with partyboat catches in three different areas and the 1973 spawning biomass estimated from the resulting regression line. The estimates derived by these alternate methods are 6,970 tons, 4,730 tons, and 6,210 tons. All estimates are below the 10,000 ton spawning population minimum and thus there is no excess by which a harvest under Section 8388.5 of the Fish and Game Code could be allowed. (17pp.

Annual fecundity, batch fecundity, and oocyte atresia of Atka mackerel (Pleurogrammus monopterygius) in Alaskan waters

Annual potential fecundity, batch fecundity, and oocyte atresia were estimated for Atka mackerel (Pleurogrammus monopterygius) collected in Alaskan waters during 1993−94. Atka mackerel were assumed to be determinate spawners on the basis of decreasing fecundity after batch spawning events. Histological examination of the ovaries indicated that oocytes in the vitellogenic stage and higher had been spawned in the current spawning season. For an average female of 40 cm, potential annual fecundity was estimated to be 41,994 eggs, average batch size (i.e., batch fecundity) was estimated to be 6689 eggs, and there were 6.13 batches per spawning season. Atresia was estimated by examining postspawning specimens and was found to be substantial. The average amount of atresia for a 40-cm fish was estimated to be 11,329 eggs, resulting in an estimated realized fecundity of only 30,664 eggs and 4.64 batches of eggs per spawning season

The Tabby cat locus maps to feline chromosome B1.

The Tabby markings of the domestic cat are unique coat patterns for which no causative candidate gene has been inferred from other mammals. In this study, a genome scan was performed on a large pedigree of cats that segregated for Tabby coat markings, specifically for the Abyssinian (Ta-) and blotched (tbtb) phenotypes. There was linkage between the Tabby locus and eight markers on cat chromosome B1. The most significant linkage was between marker FCA700 and Tabby (Z = 7.56, theta = 0.03). Two additional markers in the region supported linkage, although not with significant LOD scores. Pairwise analysis of the markers supported the published genetic map of the cat, although additional meioses are required to refine the region. The linked markers cover a 17-cM region and flank an evolutionary breakpoint, suggesting that the Tabby gene has a homologue on either human chromosome 4 or 8. Alternatively, Tabby could be a unique locus in cats