Summer Catch Research Articles

Hypolimnion Oxygenation and its Effects on the Depth Distribution of Rainbow Trout (Salmo gairdneri) and Gizzard Shad (Dorosoma cepedianum)

Abstract The hypolimnion of a quarry pond at Ottoville, Ohio, was artificially oxygenated by using a side-stream pump. Summer concentrations of dissolved oxygen were increased from almost 0 to 8 mg/liter in 1973 and were held at or above 7 mg/liter (range 7.0–21.5) in 1974; thermal stratification was maintained in both years. In previous years, when the pond was not artificially oxygenated or aerated by other means, rainbow trout (Salmo gairdneri) did not survive the summer because of high water temperature and oxygen depletion. One thousand rainbow trout were stocked after oxygenation in August 1973 and 800 stocked in May 1974. Anglers creeled several hundred fish each summer and gill net catch per effort remained constant during the study periods indicating that survival was probably high. Gill netting in February 1974 confirmed that trout were still present from the previous summer stocking. Trout were largely confined to the hypolimnion during thermal stratification, and were usually near its upper bo...

Nursery grounds of Tarakihi (Teleostei: Cheilodactylidae) around New Zealand

Abstract Nursery grounds of the tarakihi Cheilodactylus macropterus (Bloch & Schneider) were discovered in 1963–72 mainly off the south‐western coast of the North Island, in Tasman Bay, along the entire eastern coast of the South Island, and around the Chatham Islands. They occurred at depths of 20–100 m, and mostly between 10 km and 30 km from shore. The tarakihi nurseries had a dense and varied invertebrate bemthic epifauna dominated by sponges and small corals. Few signs of nurseries were found in. other New Zealand waters, in spite of the existence of major spawning grounds there. It is not known with which spawning grounds the various nursery grounds are linked. The Tasman Bay nursery ground is 18–33 km wide and about 75 km long, with a surface area of about 2000 km2. There is a rich demersal fish fauna (37 species were recorded) dominated by tarakihi, red gurnard Chelidonichthys kumu (Lesson & Garnot), snapper Chrysophrys auratus (Bloch & Schneider), and leathei'iacket Novodon convexirostris (Guenther). The young tarakihi occur at depths of 20–45 m and concentrate during winter in the warmer deeper water. They first appear in trawl catches in summer, towards the end of their first year (assumed birthdate is 1 March), and stay on the nursery until the age of 3 y. They occur in the deeper water off the nursery during their fourth and fifth year and depart during their sixth year, possibly for the spawning grounds off the west coast of the South Island. The mean lengths at the ages of 15, 27, and 39 months were 12.6, 18.0, and 24.0 cm respectively in 1970. There was some variation in growth rate within the nursery ground, but the age groups could nevertheless be recognised easily from, length frequency modes. Monthly modal lengths showed that growth slows down in winter. Evidence for fluctuations in year class strength was found; year classes 1966 and 1969 were weak and year class 1968 was strong. The vulnerability of tarakihi less than 4y old to commercial New Zealand trawl gear is low, and the local fishing fleets do no serious damage to the habitat on the nursery grounds. However, a large part of the tarakihi nursery grounds off the east coast of the South Island lies outside the territorial fishing zone. Intensive fishing on these grounds by large foreign vessels using heavy trawl gear could have an adverse effect on the habitat of the young tarakihi in this region.

Great Slave Lake: Effects of Exploitation on the Salmonid Community

A 20-year investigation commenced at the inception of the Great Slave Lake commercial fishery, and it is inferred that exploitation has been the sole cause of change in the fish stocks. Background information on the operation of the commercial fishery, the fishing regulations, and the study methods are provided. Lake whitefish, Coregonus clupeaformis, and lake trout, Salvelinus namaycush, have made up 94% of the commercial landings of 119 million lb during the period. Only three other species of the 25 occurring in the lake were usually marketed. Whitefish catches generally were distributed equally between the summer and winter seasons. Trout were caught almost exclusively during the summer season. The annual catch of these two species rose from 1.6 million lb in 1945 to a maximum of 9.4 million lb in 1949 then gradually decreased to about the 5 million lb level. The study data have been partitioned according to 13 statistical areas. Catch has not been in proportion to the extent of these areas. Whitefish catch has predominated in the western, Interior Lowlands, portion of the lake while trout catch has predominated in the eastern, Canadian Shield, portion. In various areas, the peak catches for whitefish were associated with peak catches for trout, indicating that both were the result of fishing down the virgin stocks. Summer catch per unit effort for each species has declined during the 20-year period. CPE varied with the statistical areas. The usual observed reduction for whitefish was 60% in contrast to 93% for trout. Estimated summer fishing effort and whitefish catch showed a direct relation but the relation for trout usually changed from a positive to a negative one. The average size of commercially caught fish has declined to about 2 lb for whitefish and 5 lb for trout. Information on catch per unit effort for other species indicates no evident explosions in their numbers, though ciscoes, Leucichthys spp., appear to have increased in abundance. Although the fishery was regulated in order to provide for maximum annual sustained yields, this has not been achieved for trout. Three opinions for this are offered. Exploitation under a pooled quota system for whitefish and trout is not favoured and a decrease in trout quota is recommended.

Ground Beetles1 in Cropland in South Dakota2

Ground beetles (Coleoptera: Carabidae) found in a 4-year study of cultivated fields in South Dakota included 127 species. The 14 most common species were taken in nearly the same ratios each year. Pitfall traps yielded from 0 to 15 species from each field each week during the growing season; the mean for the season was 4.8 species per week per field. In all 4 years, adult activity started to increase rapidly between August 1 and 15, reached its peak during the 1st week of September, and by September 24–30 had dropped to early summer levels. Maximum catches were 7–14 times the catches in early summer.

Survey of Rockfishes, Especially Pacific Ocean Perch, in the Northeast Pacific Ocean, 1963–66

During 1963–66, a trawl and echo-sounder survey was conducted in the northeast Pacific Ocean to investigate the distribution and abundance of rockfish (Scorpaenidae) species, particularly Pacific ocean perch (Sebastodes alutus), inhabiting the outer continental shelf and upper continental slope from Cape Blanco, Oregon, to Unalaska Island, Alaska. Rockfish predominated in most trawl catches. Among areas, numbers of rockfish species declined northward, from 19–21 in the Oregon–Vancouver Island region to 5 off Unalaska Island. Within areas, maximum numbers of species were caught at intermediate depths — usually 80–139 fath (146–254 m). With rare exceptions, Pacific ocean perch was the predominant rockfish species in the trawl catches throughout the study area, although its relative abundance declined from north to south.Within areas, ocean perch catch rates were usually maximal at intermediate depths — 120–139 fath (220–254 m) in summer and substantially deeper in winter. Juvenile fish usually occupied shallower depths than adults, but were often in the company of large adults. Among areas, summer catch rates were relatively high off southwest Vancouver Island and southeastern Alaska and in the western Gulf of Alaska. Off Vancouver Island, summer catch rates were higher than winter catch rates, particularly for large adults of both sexes. Echo-sounder records indicated schools were frequently unavailable to the on-bottom trawl used in this survey.Ocean perch in the northeast Pacific Ocean were categorized, tentatively, into B.C.- and Gulf-types, whose mutual boundary is Dixon Entrance. Separation was based on differential size distributions and year-class strengths.Survival rates among year-classes were evidently quite variable, particularly for the Gulf stock west of Cape Spencer.Qualitatively, ocean perch abundance generally increased from south to north in the study area.Bottom-water temperatures varied inversely with depth and latitude. Among areas, temperature range at depths of maximal ocean perch catch rate was 4.5–7.7 C, but in high-abundance areas the temperatures did not exceed 6.0 C. Seasonally, temperature at depths of maximal catch rate varied approximately 1.5 C.

東京湾におけるメイタガレイ卵の分布生態について

Frog-flounder, Pleuronichthys cornutus, is one of the commercially important species among flat-fish taken from Tokyo Bay. The present report deals with seasonal and geographical distributions of eggs of the species in relation to the oceanography of the area. (1) The materials on which the present study is based are planktonic samples taken by the Tokai Regional Fisheries Research Laboratory and by Kanagawa Prefectural Fisheries Experimental Station during the period from 1957 to 1962 inclusive through the cooperative investigations on important neritic-pelagic fisheries resources. The samples were collected by vertical hauls of conical plankton-nets of 45cm or 60cm in mouth diameter. The nets were usually hauled from a depth of 150m or the ocean bottom when it was shallower than that up to the sea surface. (2) The eggs occur during the period from the late October till the early part of the following January. The peak appears during the period from the mid-November till the mid-December. The positive areas are the shallow zones on both east and west sides of the entrance of Tokyo Bay. None of eggs are found from the inner part of Tokyo Bay and Sagami Bay. (3) The ranges of temperature for occurrence are 16-21°C and those of chlorinity, 18-19‰. Thus, the positive area corresponds to the neritic zones where the water from the open sea does not strongly affect. The eggs are distributed neither in the low chlorinity region (inner part of Tokyo Bay) nor in the Sagami Bay which accepts the influence of open sea water directly. (4) The eggs of this species are spawned at around the entrance of Tokyo Bay. And this species grows in that area or after enterde into the bay, No commercial catch of this species is taken from the innermost part of the bay. There are two modes in the length composition of the summer catch from Tokyo bay, i. e. at around 16-20cm and 8-14cm in total length. These schools likely emigrate from the inside of the bay towards the entrance of the same in season of November-December. The larger fishes are considered to be mature there and become the spawners.

ビンナガマグロ漁況との關係(第 1 報)

Based mainly on the latest materia's given by the local fisheries authorities in l'refs. Siduoka, Kanagawa, etc. we have investigated the catch of ‘Binnaga Maguro’ (Germo germo (Lacepede)) in relation to the hydrographical conditions. The seasonal variations of the catch of ‘Binnaga’ in every year are nearly of the same type (Fig. 1); the so-called winter season begins in October, showing its flowering season from Dec. to Feb., and ends in the middle decade of April. And the so-called summer season begins from the late April, showing its flowering season in the interval from middle May to middle June, and ends in July. Inspecting Fig. 2 we notice the remarkable decline of the summer catch (landed mainly at the harbours in Siduoka Pref.) in the adjacent waters of Japan. On the other hand, the winter off-shore fishing grounds were extended year by year to the east with the increase of the landings, and now cover the waters distant about 2, 000 sea-miles from our coast. The former fishing ground moves north-easterly from spring to summer with the advance of Kur03iWO, while the latter (in winter) accumulates in the regions along the line of subtropical convergence. Apparently we can see the fishing grounds during the whole year rotating in the anti-cyclonic sense with the run of Kurosiwo and its back current of salty water-masses. The optimum water temperature of the catch lies at 17°-19°C (max. at about 18°C) in Nov. -Feb., but lying at 18°-21°C (max. at about 20°C) in May and June. The catch represents 2 maxima in winter, one at the salinity of 34•6-14•9% and the other above 35•5%, while in summer only one at 34•8 %. The shoals distributed in the region comparatively near the land lack the large-sized fishes and contain more small-sized ones than off-shore shoals. In conclusion, summarizing the above mentioned facts, the writer (M. UDA) proposes the following hypothetical theory on the migration of Binnaga Maguro, following the instructions kindly given him by Dr. M. TAUTI: There are two partially inter-related stocks, one in the waters near the land (I) and the other in the offing (II). The former consists of the native stock A0 and the incoming stock from (II) B' (of small and partially of middle-sized fish), while the latter (II) consists of the native stock BO and the incoming stock from (I) A' (of medium and partially of small sizes). The recent overfishing of (I), particularly of A, , caused the decline of the yield of `Binnaga Maguro' in summer.

FURTHER NOTES ON THE BUTTERFLIES OF SOUTHERN NEWFOUNDLAND

The Diurnals of southern Newfoundland were briefly commented upon last year (1935, Can. Ent. LXVII : 82). Another summer's catch by the same collector at Doyles Station has increased the number of species reported from the Island by two and possibly helped to clear up the confusion in the genus Lycaena.

Sixth Annual Report of the Fishery Board for Scotland

THE Report for 1887 is published in three separate parts—a A plan which will be found convenient in many ways. Part I. contains the General Report; Part II., Report on Salmon Fisheries; and Part III., the Scientific Investigations. The product of the sea-fisheries of Scotland continues to be very large, but in 1887 the prices of most kinds of fish were much lower than they had been for a great many years previously; the fishermen only received a very small return for their capital and labour, and many of them were reduced to a state of extreme poverty. Of the different fisheries of Scotland, that of the herring continues to be by far the most productive and valuable. The fishing of 1887 was less so than that of 1886, but, owing to the great depression in the herring trade, it was not entered into nor carried on with the spirit and industry of more prosperous times. The summer's catches of herring were, speaking generally, much inferior to those of 1886, but the winter herring fishery was the most productive ever known. With yearly fluctuations, the yield of the herring fishery on the Scottish coast has, since the beginning of the century, gone on increasing in an extraordinary degree. The total quantity of white fish landed and sold for consumption fresh showed a large increase compared with 1886; being the largest landed in any year during which returns have been collected; whilst the shell-fish showed a considerable decrease. The total gross value of the sea-fisheries of Scotland for 1887 was,£1,915,602 10s. The Board are much impressed with the beneficial results to fishermen and curers arising from increased telegraphic communication, which, when further developed, will be of immense value for the promotion of the fishing industry. It is satisfactory that thirteen new telegraph stations are to be opened in remote districts; also that a number of harbours are being improved or constructed. The marine police and fishery superintendence was carried on by H. M. SS. Jackal, Vigilant, Firm, and Active.