Southern Blue Whiting Micromesistius Australis Research Articles

Eating catch of the day: the diet of porbeagle shark Lamna nasus (Bonnaterre 1788) based on stomach content analysis, and the interaction with trawl fisheries in the south-western Atlantic (52° S-56° S).

This work examined the diet of the porbeagle shark Lamna nasus in the south-west Atlantic Ocean (SWAO, Argentina, 52° S-56° S) by analysing the stomach content information obtained by scientific observers who sampled specimens captured as by-catch on-board commercial fishing vessels from 2010 to 2020. A total of 148 fishing sites were analysed, in which the estimated catch was composed mainly of hoki Macruronus magellanicus (56.00%) and southern blue whiting Micromesistius australis (33.13%). From 413 porbeagle sharks sampled (292 females and 121 males) ranging from 71 to 241 cm total length (LT ) (mean: 179.76 ± 26.74 cm), 310 (75.06%) contained food in the stomachs. The forage fish were mainly hoki M. magellanicus (23.53%) and southern blue whiting M. australis (19.05%), followed by the Patagonian sprat Sprattus fuegensis (4.48%) and nototheniids (1.4%). Cephalopods and crustaceans accounted for 10% of the diet. The estimated trophic level was 4.35. Generalized linear models revealed that the consumption of hoki M. magellanicus and southern blue whiting M. australis increased with the LT of the porbeagle shark. Moreover, smaller porbeagle sharks preyed upon both small and large teleost fish, whereas larger porbeagle sharks predated exclusively upon large fish. The diet of porbeagle shark involved interactions with fisheries as it fed upon the fish species that constituted the main catch in the analysed fishing sites, as well as the main catches of the austral trawl fisheries. The ecological role of porbeagle shark observed in the SWAO exposed implications for fisheries management from a multispecies perspective.

New insights on feeding habits of the southern blue whiting Micromesistius australis Norman, 1937 in eastern South Pacific waters

Journal of Applied IchthyologyVolume 34, Issue 3 p. 694-697 SHORT COMMUNICATION New insights on feeding habits of the southern blue whiting Micromesistius australis Norman, 1937 in eastern South Pacific waters S. A. Klarian, Corresponding Author S. A. Klarian sebastian.klarian@unab.cl Facultad de Ecologia y Recursos Naturales, Centro de Investigacion Marina Quintay, Universidad Andres Bello, Viña del Mar, Chile Facultad de Ecologia y Recursos Naturales, Centro de Investigacion para la Sustentabilidad CIS, Universidad Andres Bello, Santiago, Chile Laboratorio de Analisis Isotopico (LAI), Universidad Andres Bello, Viña del Mar, Chile Correspondence Sebastian A. Klarian, Centro de Investigacion Marina Quintay, Facultad de Ecologia y Recursos Naturales, Universidad Andres Bello, Chile. Email: sebastian.klarian@unab.clSearch for more papers by this authorB. E. Molina-Burgos, B. E. Molina-Burgos Facultad de Ecologia y Recursos Naturales, Centro de Investigacion para la Sustentabilidad CIS, Universidad Andres Bello, Santiago, ChileSearch for more papers by this authorA. Saavedra, A. Saavedra Instituto de Fomento Pesquero, Valparaiso, ChileSearch for more papers by this authorP. Galvez, P. Galvez Instituto de Fomento Pesquero, Valparaiso, ChileSearch for more papers by this authorR. Vargas, R. Vargas Instituto de Fomento Pesquero, Valparaiso, ChileSearch for more papers by this authorR. Melendez, R. Melendez Facultad de Ecologia y Recursos Naturales, Centro de Investigacion Marina Quintay, Universidad Andres Bello, Viña del Mar, ChileDeceasedSearch for more papers by this authorE. T. Schultz, E. T. Schultz Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USASearch for more papers by this author S. A. Klarian, Corresponding Author S. A. Klarian sebastian.klarian@unab.cl Facultad de Ecologia y Recursos Naturales, Centro de Investigacion Marina Quintay, Universidad Andres Bello, Viña del Mar, Chile Facultad de Ecologia y Recursos Naturales, Centro de Investigacion para la Sustentabilidad CIS, Universidad Andres Bello, Santiago, Chile Laboratorio de Analisis Isotopico (LAI), Universidad Andres Bello, Viña del Mar, Chile Correspondence Sebastian A. Klarian, Centro de Investigacion Marina Quintay, Facultad de Ecologia y Recursos Naturales, Universidad Andres Bello, Chile. Email: sebastian.klarian@unab.clSearch for more papers by this authorB. E. Molina-Burgos, B. E. Molina-Burgos Facultad de Ecologia y Recursos Naturales, Centro de Investigacion para la Sustentabilidad CIS, Universidad Andres Bello, Santiago, ChileSearch for more papers by this authorA. Saavedra, A. Saavedra Instituto de Fomento Pesquero, Valparaiso, ChileSearch for more papers by this authorP. Galvez, P. Galvez Instituto de Fomento Pesquero, Valparaiso, ChileSearch for more papers by this authorR. Vargas, R. Vargas Instituto de Fomento Pesquero, Valparaiso, ChileSearch for more papers by this authorR. Melendez, R. Melendez Facultad de Ecologia y Recursos Naturales, Centro de Investigacion Marina Quintay, Universidad Andres Bello, Viña del Mar, ChileDeceasedSearch for more papers by this authorE. T. Schultz, E. T. Schultz Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USASearch for more papers by this author First published: 22 December 2017 https://doi.org/10.1111/jai.13598Citations: 2 Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume34, Issue3June 2018Pages 694-697 RelatedInformation

Temporal variations of potential fecundity of southern blue whiting (Micromesistius australis australis) in the Southeast Pacific

Fecundity is a key aspect of fish species reproductive biology because it relates directly to total egg production. Yet, despite such importance, fecundity estimates are lacking or scarce for several fish species. The gravimetric method is the most-used one to estimate fecundity by essentially scaling up the oocyte density to the ovary weight. It is a relatively simple and precise technique, but also time consuming because it requires counting all oocytes in an ovary subsample. The auto-diametric method, on the other hand, is relatively new for estimating fecundity, representing a rapid alternative, because it requires only an estimation of mean oocyte density from mean oocyte diameter. Using the extensive database available from commercial fishery and design surveys for southern blue whiting Micromesistius australis australis in the Southeast Pacific, we compared estimates of fecundity using both gravimetric and auto-diametric methods. Temporal variations in potential fecundity from the auto-diametric method were evaluated using generalised linear models considering predictors from maternal characteristics such as female size, condition factor, oocyte size, and gonadosomatic index. A global and time-invariant auto-diametric equation was evaluated using a simulation procedure based on non-parametric bootstrap. Results indicated there were not significant differences regarding fecundity estimates between the gravimetric and auto-diametric method (p > 0.05). Simulation showed the application of a global equation is unbiased and sufficiently precise to estimate time-invariant fecundity of this species. Temporal variations on fecundity were explained by maternal characteristic, revealing signals of fecundity down-regulation. We discuss how oocyte size and nutritional condition (measured as condition factor) are one of the important factors determining fecundity. We highlighted also the relevance of choosing the appropriate sampling period to conduct maturity studies and ensure precise estimates of fecundity of this species.

From small bycatch to main commercial species: Explosion of stocks of rock cod Patagonotothen ramsayi (Regan) in the Southwest Atlantic

The Patagonian Shelf ecosystem is considered to be a wasp-waist ecosystem controlled by medium-sized planktivores Patagonian squid Doryteuthis gahi, rock cod Patagonotothen ramsayi, and southern blue whiting Micromesistius australis. After the collapse of southern blue whiting stocks in 2004–2007, its role was overtaken by rock cod, which exhibited a 20–30 fold increase in catches and CPUEs. P. ramsayi is an important food source for all predatory fish; representing about half of the food consumption in hakes, toothfish, kingclip, and some skates. Its importance increases with increasing size of predator with rock cod gradually substituting a similar-sized squid. The explosion of rock cod abundance coincided with an increase of seasonal immigrants preying on this species (hakes and kingclip) that may have changed their migratory timing and patterns for better use of this food resource.

Variación geográfica de las comunidades de parásitos de la merluza de tres aletas Micromesistius australis al sur de Sudamérica

A comparative analysis of the parasite fauna of the southern blue whiting Micromesistius australis was carried out on 165 specimens caught around the souther...

Segregation of SE Pacific and SW Atlantic southern blue whiting stocks: integrating evidence from complementary otolith microchemistry and parasite assemblage approaches

Southern blue whiting Micromesistius australis support one of the largest industrial fisheries in South America. Two main spawning/nursery grounds are known: one in the SW Atlantic Ocean (SWA), southwest from the Falkland (Malvinas) Islands; and other in the SE Pacific Ocean (SEP), south from the Taitao Peninsula. Juveniles originating from both grounds are believed to mix during migration and/or in feeding areas in the Scotia Sea. Previous efforts to distinguish stocks in this area have yielded contradictory results between genetics and otolith microchemical analyses. In the present work we revisited the null hypothesis of a single stock occurring in the broader SWA-SEP region by comparing and integrating results from different approaches: trace metals (Ca, Sr, Ba, Mg, Mn) and stable isotopes (δ13C, δ18O) in otolith cores, and parasite assemblage compositions in adults from SWA and SEP spawning grounds. We found significant differences in Sr:Ca, δ13C and δ18O mean ratios between spawning grounds. The best trace element discriminant model classified 83% of the samples. Each stable isotope discriminated >90% of the samples, while combining them into a bivariate discriminant model led to 100% classification success. Higher δ18O levels in the SWA samples agreed with lower mean temperature and higher ambient δ18O levels in that area. Parasite assemblage compositions also showed significant differences between grounds regarding the prevalence of Chondracanthus, Contracaecum, Hepatoxylon and Grillotia and the abundance of Diclidophora, Anisakis, Contracaecum, Hysterothylacium and Hepatoxylon. Parasite-based discriminant models supported 90–100% correct assignment of samples to capture location. Although preliminary due to limited sampling coverage, our results support the existence of at least two ecologically distinct sub-populations of southern blue whiting in South America. The joint use of otolith microchemistry and parasitological techniques showed to be a promising way to test hypotheses concerning ecological stocks in marine fishes.

Resource partitioning by two large planktivorous fishes Micromesistius australis and Macruronus magellanicus in the Southwest Atlantic

The ontogenetic, seasonal, bathymetric and regional variations in the feeding spectrum of 922 specimens of southern blue whiting Micromesistius australis and 512 specimens of hoki Macruronus magellanicus were studied on the Falkland Islands’ shelf (Southwest Atlantic) between November 1999 and April 2003. A total of 49 different prey items were found in the stomach contents of the two species, with the hyperiid Themisto gaudichaudii and Euphausiacea being amongst the most important prey. Although the species composition did not change over fish size, the proportions of individual prey items in their diets did, with an increase in T. gaudichaudii and Euphausiacea with increasing fish size in southern blue whiting. The opposite occurred in hoki. Seasonal variations in the diet were found to mirror the seasonal abundance of prey around the Falkland Islands for the two species. Intra-specific differences in the diet of both predators reflected the distribution of prey, which in turn was determined by the water structure in the two regions sampled, leading to very different diets. In the limited time that the two species occupied the same space there was little or no competition resulting in almost total segregation of their trophic niches in space and time.

Influence of Drake Passage oceanography on the parasitic infection of individual year-classes of southern blue whiting Micromesistius australis

Southern blue whiting Micromesistius australis occurs around the southern coasts of South America and has been known to undertake summer feeding migrations to the Antarctic Penin- sula and South Orkney Islands. The largest stock spawns to the southwest of the Falkland Islands and has been the subject of a major fishery on the Patagonian Shelf since 1978. Fish are infected with cysts of the Myxosporean parasite Kudoa alliaria which make the flesh commercially unattractive for fillets. A 10 yr study initiated in 1989 established that prevalence of the parasite is over 80% for fish older than 1 yr, and that average infection intensities are about 14 cysts per fish. We constructed a combined generalised linear/generalised additive model (GLM/GAM) of parasite abundance in M. australis. The combination of up to 30 ages and 8 yr of data spanning 10 yr allowed us to investi- gate rates of parasitism in 33 individual cohorts. Strong age and cohort effects in the model implied that the fish acquire parasites in their first 1 to 1 1 /2 yr of life and that parasite abundance is set at these ages for the lifetime of the cohort. Several cohorts have statistically significantly lower parasite abun- dance than the majority, and these instances are roughly coincident with the 7 yr periodicity of sea- ice and sea surface temperature (SST) fluctuations in the Drake Passage. There are significant corre- lations between SST in the Drake Passage, the duration of sea-ice around Signy Island (South Orkney Islands) with a 1 yr time lag and parasite abundance in a cohort. We hypothesise that these correla- tions represent changes in the distribution and density of adult M. australis in warm and cold years, which thereby influences the density of the parasite field that juvenile fish encounter.

Age and growth of the southern blue whiting <i>Micromesistius australis</i> in the SW Atlantic

Age and growth of southern blue whiting Micromesistius australis are studied. Sagitta otoliths from 3650 specimens were used for age determination. These were taken during research surveys and commercial catches in the South West Atlantic during 1994 and 1995. The size of fishes ranged from 17 to 60 cm total length, corresponding to ages 0 to 23 years. Females attained a greater asymptotic length (L ? 59.74 cm) than males (L ? 54.72 cm). Comparison of growth curves by the likelihood ratio showed that the differences among females and males were due to the asymptotic length, while the other parameters (K and t0) were not statistically different. The mean weight-at-age, mean length-at-age, and total mortality (Z) were estimated. Growth parameters estimated by sex in the period 1994-95, mean size per age group, and the number of individuals per age in the catches show differences with those calculated when the population was in the early stage of exploitation. A predominance of 2 to 9 year old individuals was observed in the total catches in 1994-1995, whereas in the beginning of the fisheries total catches were basically fish 15 to 19 years old.

Exploratory deep‐sea fishing in the Falkland Islands, south‐western Atlantic

Records of demersal deep‐sea fish assemblages in waters around the Falkland Islands (Patagonian shelf area) are rare. Twenty deep‐water stations to the east and south of the Falkland Islands were sampled by commercial bottom trawl deployed in upper, middle and lower benthopelagic zones (depth range of approximately 500‐1000 m). Forty‐one species (22 families) of teleost fish were recorded, 10 species (two families) of elasmobranch and one species of agnathan. Different assemblages of fish were found to characterize each depth zone (e.g. Moridae in deeper waters, Bothidae and Rajidae in shallower waters), with diversity being greatest in the mid‐zone and biomass greatest in the upper and lower zones. Some species occurred in all zones but showed depth‐related abundance. Four species, namely the grenadiers Macrourus carinutus and Coelorhynchus fasciatus, the southern blue whiting Micromesistius australis, and the Patagonian toothfish Dissostichus eleginoides, accounted for 85% by weight of all fish caught. Quantitative sampling of selected species revealed depth‐related variations in their population structure. Length‐frequency analyses are presented for M. carinatus and D. eleginoides and show a tendency for larger individuals to inhabit deeper water. Discard rates from the commercial catch were sometimes high, particularly for the smaller species, raising concerns about the impact of a fishery on by‐catch species. The potential for deep‐sea fisheries in Falkland waters is discussed and further studies are suggested in the light of developing oil, gas and fishing industries. The presence of some invertebrate taxa is recorded.

Utilization of offal and discards from “finfish” trawlers around the Falkland Islands by the Black‐browed Albatross Diomedea melanophris

Multinational fisheries operating in the vicinity of the Falkland Islands currently take c. 90,000 tonnes of true fish (“finfish” as opposed to squid) per annum, including hakes Merluccius spp., Southern Blue Whiting Micromesistius australis, Hoki Macruronus magel‐lanicus and Red Cod Salilota australis, and generate substantial quantities of fisheries waste in the form of discards and offal. This paper examines the use made of this waste by scavenging Black‐browed Albatrosses Diomedea melanophris which breed in the Falklands. The various types of waste produced are described and their consumption by scavenging albatrosses is quantified. The results indicate that Black‐browed Albatrosses obtain c. 8000 tonnes of food per annum from this source, of which two‐thirds is offal and the remainder whole discards. The energy content of this waste is equivalent to 4.4% of the estimated total annual energy requirements of the Falklands Black‐browed Albatross population. However, as the fishery is a greater predator of finfish stocks than are the albatrosses, its long‐term impact may be detrimental to these birds.

The diet of Patagonian hake Merluccius australis polylepis and its daily ration of Patagonian grenadier Macrouronus magellanicus

The diet of the Patagonian hake Merluccius australis polylepis in 1986 was determined by analysis of stomach samples collected from commercial trawl catches. The major prey items were Patagonian grenadier Macrouronus magellanicus and, to a lesser extent, southern blue whiting Micromesistius australis. Large (81–100 cm) hake are mainly piscivorous and consume more grenadier than smaller (51–80 cm) hake. The smaller hake feed both on fish and invertebrates. There was no difference by sex in terms of stomach contents. The daily feeding cycle was also investigated from samples collected during 1991. Hake feed principally on 1-, 2-, and 3-year-old grenadier, which they seem to catch mainly at night. The daily ration of grenadier was between 0,043 and 0,26 per cent of body mass (1,692–9,849 g). The results are similar to those for other hake species in terms of composition of the diet, daily feeding cycle and daily ration.

Quantitative analysis of the use of discards from squid trawlers by Black‐browed Albatrosses Diomedea melanophris in the vicinity of the Falkland Islands

In the past decade, a major trawl fishery for the squid Loligo gahi has developed in the vicinity of Beauchêne Island, an internationally important breeding site for the Black‐browed Albatross Diomedea melanophris. The breeding season diet of this albatross in the Falklands and its use of discards generated by the Loligo fishery were investigated. Albatross chicks are fed extensively on commercially exploited species of squid and fish including Loligo gahi and southern blue whiting Micromesistius australis. The quantity of waste generated by the Loligo fishery amounts to c. 5% of the reported catch and just over 50% of this waste, mainly Loligo and nototheniid fish, is scavenged by adult Black‐browed Albatrosses. The total quantity scavenged during the chick rearing period amounts to 1000–2000 tonnes per year. This is equivalent to 10–15% of the total food requirement of the breeding Black‐browed Albatross population on Beauchene Island during the period when the fishery is operating. Although the Loligo fishery currently provides a significant quantity of food to these albatrosses, its net effect may be detrimental to them, as it is a much greater predator of Loligo stocks than the albatrosses are estimated to have been prior to the fishery's development.

Morphometry of southern blue whiting Micromesistius australis (Norman, 1937)-from the region of Burdwood Bank

Morphometry of southern blue whiting Micromesistius australis (Norman, 1937)-from the region of Burdwood Bank

Occurrence of .BETA.-alanine betaine in the muscles of New Zealand whiptail and southern blue whiting.

β-Alanine betaine (β-homobetaine) was is isolated in crystalline form from the white muscles of two species of fish, New Zealand whiptail Macruronus novaezelandidae and southern blue whiting Micromesistius australis, and identified on the basis of comparison of melting point, Rf values in TLC, IR and mass spectra with the synthetic specimen. It was not detected, however, in the muscles of cod, New Zealand hake, flatfish, big-eye tuna, and jack mackerel. These results may indicate that the distribution of β-alanine betaine in fish is limited.