The goal of the work is to investigate the role of threespine stickleback Gasterosteus aculeatus in the transfer of substances and energy between the open sea and coastal communities in the White Sea. Five main coastal biotopes habitats in the White Sea were described and their role in spawning of stickleback was evaluated. Almost all sticklebacks (1.9 billion) spawn in the western part of the sea. Approaching the inshore zone to spawn, stickleback brings a significant amount of substance and energy – 6200 tons in fish bodies and 800 tons in eggs. Coastal predators utiliz only 1–2% of this due to their low numbers. The stickleback itself consumes 90–95% of the spawned eggs mainly by destroying nests. Since the stickleback eats mostly its own eggs, it put a low pressure on the coastal prey organisms. The main mortality of stickleback occurs after spawning in the open sea.

Genetic markers (sex-specific loci of Ga1 and Ga2) have been used to analyze the sex ratio of the threespine stickleback at different stages of ontogenesis. The progeny of all individually tested females includes both males and females, and no significant departures from a 1 : 1 sex ratio has been found in embryos from the natural nests. Juveniles did not demonstrate a sex bias up to one-and-a-half or two months of age, but in older juveniles, females prevailed (this fact has been reported for the first time). Females prevail among spawners, which mostly results from the predominant elimination of males during the spawning and post-spawning periods. The possible causes of this predominance are discussed.

Проведена количественная оценка метацеркарий трематод рода Cryptocotyle на поверхности тела у трехиглой колюшки Gasterosteus aculeatus Кандалакшского залива Белого моря. для работы были выбраны три нерестилища, отличающиеся по сочетанию ключевых характеристик среды, влияющих на плотность производителей. отлов рыб проводили трехкратно в течение нерестового периода с 29 мая по 7 июля 2016 г. в начале нереста характеристики заражения у рыб из разных местообитаний были очень сходны, что, скорее всего, указывает на смешивание колюшки во время зимовки. впоследствии во всех биотопах к концу нереста отмечалось увеличение как индекса обилия паразитов (среднее число паразитов на рыбу, включая незараженных особей), так и экстенсивности заражения (доля зараженных рыб). самые высокие значения индекса обилия и экстенсивности заражения наблюдали в лагуне Колюшковая, отличающейся от других нерестилищ колюшки значительной степенью изолированности от моря и замедленным водообменом, способствующими накоплению паразитов у особей. отсутствие у колюшек половых различий по степени заражения указывает на то, что хотя самцы и самки несколько отличаются в отношении пространственного распределения в разные периоды нереста, эти различия недостаточны для того, чтобы привести к различиям в зараженности. отсутствие достоверной связи между индивидуальной зараженностью и размерами тела, вероятно, объясняется высокой вариабельностью размеров рыб разного возраста.

This review summarizes and analyzes data on the threespine stickleback Gasterosteus aculeatus L. of the White Sea, which is currently the most abundant fish in the region and, therefore, plays an important role in inshore and offshore communities. The threespine stickleback was abundant in the 1920s–1940s; its numbers declined significantly between the late 1960s and late 1990s and have increased again since then, showing a positive correlation with water temperature. In order to reveal the mechanisms of changes in the population of this species and to assess its role in the marine ecosystems, various aspects of the population biology of the species (interannual and seasonal population dynamics, spatial heterogeneity, age and sex structure, lipid and fatty acid status, homing, and fluctuating asymmetry), as well as its interactions with other organisms (feeding characteristics of adults and juveniles, role in feeding predatory fish, association with eelgrass, parasite composition and spatial distribution, and relationships with competing species) are analyzed.

Certification according to the standards of the Marine Stewardship Council (MSC) is highly demanded in the world market of seafood products. In Russia, a number of fisheries already have MSC certificates, but still there is a significant potential for certification of other fisheries. This requires analysis of the experience of companies that have successfully obtained the certification. Special attention should be paid to small-scale fisheries, whose financial opportunities to participate in certification programs, unlike large fisheries, are seriously limited. In the present work, process of ecological certification of fishery is considered on an example of the gillnet fishery of European perch Perca fluviatilis in the Irikla Reservoir, located in the middle course of the river Ural in the Orenburg Province. The catch volume of perch is 200–250 metric tons during the recent years. Fishing companies that fish in this reservoir have been working on MSC certification for over ten years. Process of certification has shown that the fishery meets the necessary standards, but even after the certification completed in 2016, there is a need for certain activities to support certification. These are in-depth analysis of the recreational fisheries, development of research plans in cooperation with scientific fishery institutes, specifically aimed at informing the certification process, independent analysis of the fisheries management system, detailed study of various bycatch species. It can be concluded that positive experience of this small-scale fishery with ecological certification can be important in improving fisheries management not only in Russia but also worldwide.

Hypothesis: Fluctuating asymmetry (FA) - random deviations from perfect symmetry that are used as a measure of developmental stability - is an effective indicator of stress and fitness in threespine stickleback. Organisms: The threespine stickleback (Gasterosteus aculeatus) and two other species, the brook stickleback (Culaea inconstans) and ninespine stickleback (Pungitius pungitius), were the focus of a review of the literature. In addition, four populations of G. aculeatus - one anadromous population from the Kamchatka River, two marine populations from the White Sea, and one freshwater population from the White Sea basin - were studied in the field. Methods: A review of the literature relating fluctuating asymmetry to different variables, and a comparison of fluctuating asymmetry in four populations of stickleback, which differed in geographical distribution and life history, using lateral plates and four cranial bones (operculum, lachrymal, third suborbital, quadrate). Results: An appraisal of the literature on fluctuating asymmetry suggests that decreasing interest in FA studies has likely resulted from conflicting research results. To some extent, this problem is likely caused by the morphological structures used in FA analysis, which are generally limited to the lateral plates and pelvic fins. These structures can evolve quickly in response to various environmental changes, thus their fluctuating asymmetry reflects not only individual fitness and stress, but also multiple uncontrolled factors that may directly affect those same structures. Using four cranial bones in our analysis showed lower fluctuating asymmetry in anadromous stickleback from the Kamchatka Peninsula compared with marine and freshwater stickleback from the White Sea and its basin. This may be caused by more favourable feeding conditions in the North Pacific than in the White Sea. The different environmental conditions at these locations did not appear to have a significant effect on fluctuating asymmetry, although the comparison of freshwater, anadromous, and marine populations showed that the fluctuating asymmetry of the structures we used is responsive to these differences. Our FA analysis of the selected bone structures reveals clear heterogeneity in stickleback with different life histories. We suggest that these structures can be considered reliable for studies of fluctuating asymmetry in stickleback fishes.

Hypothesis: Selective sex-related mortality of the marine threespine stickleback in the White Sea causes the female-biased sex ratio observed on the spawning grounds. Organisms: Adult threespine stickleback (Gasterosteus aculeatus) spawning in the inshore zone, and three species of predatory fishes: Atlantic cod (Gadus morhua), shorthorn sculpin (Myoxocephalus scorpius), and fourhorn sculpin (Myoxocephalus quadricornis). Place and times: Kandalaksha Bay, White Sea, Russia; June to August 2012–2018. Methods: The following sampling methods were used: beach seining to determine fish density and local population size, hand collection of dead fish on the spawning grounds, gill netting of predatory fishes, analysis of predatory fish stomach contents to determine the sex of wellpreserved stickleback, and morphological analysis of stickleback spines to determine the sex of decomposed stickleback. Results: The dynamics of stickleback abundance in the lagoon is explained by inshore migration of the fish to the spawning area at the beginning of the spawning period, and their subsequent departure at the end of the spawning season, with females leaving the grounds earlier than males. During spawning (5–30 June), total stickleback mortality reaches about 0.1%; the difference in the relative mortality rates of 0.0044% per day for males and 0.0030% for females is statistically significant. Mortality increases in the post-spawning period, when fish abundance in the inshore zone falls considerably, but remains at a very low level. Because of the low level of non-predation mortality, it cannot be the cause of the female-biased sex ratio observed in the White Sea stickleback population. Predation-associated mortality caused by Atlantic cod and sculpins was male-biased. Based on the stomach contents of predatory fish, the sex ratio of stickleback prey was as follows: cod, 61% males/39% females; sculpins, 82% males/18% females, which was significantly different from the population at sea (35% males/ 65% females). This factor alone, however, is unlikely to explain the prevalence of female stickleback in the lagoon. The eventual offshore male-biased mortality, caused by increased depletion of energy reserves during the spawning period, is probably the main reason for the observed female-biased sex ratio. Correspondence: P.V. Golovin, Saint-Petersburg State University, 16 line V.O. 29, St. Petersburg 199178, Russia. email: pasha-golovin@yandex.ru Consult the copyright statement on the inside front cover for non-commercial copying policies. Evolutionary Ecology Research, 2019, 20: 279–295 © 2019 Pavel V. Golovin

Hypothesis: Marine threespine stickleback manifest homing ability and site fidelity during their spawning period. Organism: The threespine stickleback, Gasterosteus aculeatus. Time and places: June 2015 and June 2016 (during the stickleback spawning period), Koliushkovaya Lagoon, Kandalaksha Bay, the White Sea. Methods: Stickleback were tagged on their inshore spawning grounds about 2 weeks after their inshore migration. We attached plastic tags to their dorsal spines, displaced them 100-300 m away from shore, and recaptured them inshore after periods of one hour to four days. Results: Stickleback caught on their spawning grounds in the lagoon, tagged and displaced a few hundred metres, were able to return to their home site within a day. Males and females exhibited no differences in homing ability. Most fish left their home site within four days of returning, however, indicating that site fidelity is weak. Stickleback caught outside the lagoon in the sea, and tagged and released in the lagoon, spread along the shore in accordance with the density of local fish.

This study uses morphometric analysis for better understanding processes occurring during the spawning period in the population of threespine stickleback Gasterosteus aculeatus. Totally, 270 specimens were sampled in 2016 in the Keret Archipelago (White Sea) from three spawning grounds of different quality in the beginning (28–30 May), middle (15–17 June) and end (7–9 July) of spawning period. Nine characters describing fish body shape were measured on each specimen using scanned image and caliper: 1) Total Length, 2) Standard Length, 3) Head Length, 4) Maxilla Length, 5) Distance Between Head and Pectoral Fin, 6) Body Depth, 7) Body Thickness, 8) Head Thickness, 9) Caudal Length. For analyses, we used ratio of characters 3–9 to Standard Length. Principal Component Analysis has separated several groups of characters, describing the upper part of the body (Characters 3–5), body volume (Characters 6–8), and Caudal Length (9). Separation of the groups was similar in both sexes. All groups of characters showed notable changes during the spawning period. In the beginning, the spatial heterogeneity of samples was low, meaning that in wintering locations the population is not structured. In the middle of spawning season, the highest heterogeneity was observed. Males characterized by larger upper part of the body and larger size, were numerous in high quality spawning grounds (characterized by high density of sea grass and stickleback). This probably results from a competition between territorial males for higher quality spawning grounds. In the end of spawning period no spatial heterogeneity was observed, probably, because most of stickleback left the spawning grounds and no competition for higher quality spawning grounds took place. Spatial heterogeneity was somewhat lower in females, but also statistically significant in several cases. Group of characters describing body volume, in general, showed the decline during the spawning period, reflecting release of eggs in females and loss of energy associated with spawning (more pronounced in males guarding their progeny). Superimposition of several processes, such as competition for fish for better spawning grounds, release of eggs and loss of energy associated with spawning, and inshore and offshore migrations, results in a dynamic and complicated picture of morphological heterogeneity occurring during the spawning season of the threespine stickleback.

Hypothesis: Stickleback abundance in the White Sea is limited by availability of spawning habitats.Organisms: Threespine stickleback, Gasterosteus aculeatus; eelgrass, Zostera marina.Times and places: June (spawning period of stickleback) 2009-2011 and 2014; 60 locations along the White Sea coast.Methods: We sampled with a beach seine (length 7.5 m, height 1.5 m, mesh size 5 mm in wings and 1 mm in purse) in coastal zones within 30 m of the shore.Results: Around 60% of the entire stickleback population occurs in the northwestern part of the White Sea (Kandalaksha Bay). This region has favourable spawning habitats, i.e. protected inlets with a high density of eelgrass and other macrophytes. Other parts of the White Sea are more exposed to waves and have less vegetation. We estimated that the White Sea currently supports about 740 million stickleback at the beginning of the spawning season, with a total biomass of about 1600 metric tonnes.

A comparative literature review on methods of age reading in fishes, suggests that the technique based on study of growth rings on sagittal otoliths is the most promising for three-spined stickleback. This technique was used to study the variability of the White Sea stickleback age estimates by different operators. Similarity of age structure of the experimental sample obtained by four operators suggests that in order to correctly describe age structure of population, a preliminary training of operators is an obligatory component of analysis. For studies requiring precise determination of individual age, it is necessary to made several replicates of the analysis to reduce sampling error. Refs 23. Figs 11. Tables 4.