Laboratory guide to early life history stages of northeast Pacific fishes

This laboratory guide presents taxonomic information on eggs and larvae of fishes of the Northeast Pacific Ocean (north of California) and the eastern Bering Sea. Included are early-life-history series, illustrations, and comparative descriptions of 232 species expected to spawn here, out of a total 627 species known to occur in marine waters of this area. Meristic and general life-history data are included, as well as diagnostic characters to help identify eggs and larvae. Most of this information has been gleaned from literature, with the addition of 200 previously unpublished illustrations. (PDF file contains 654 pages.)

Survey of fish protective facilities at water withdrawal sites on the Snake and Columbia Rivers

Proliferation of water withdrawals and new pump intake and screen designs has occurred with the growth of irrigated agriculture along the Columbia and Snake Rivers. Concern for the protection of anadromous and resident fish populations resulted in formulation of a survey of the water withdrawal systems. The survey included distribution studies of juvenile fish near pump sites and field inspection of those sites to determine adequacy of screening for protection of fish. A total of 225 sites were inspected in 1979 and 1980, with a follow-up inspection of 95 sites in 1982. Results indicated a definite trend toward lack of concern for the condition of fish protective facilities. Only 4 out of 22 sites not meeting criteria in 1979 had been upgraded to acceptable conditions. Of more concern, 13 of the sites meeting criteria in 1979 were below criteria when reinspected in 1982. Some of the discrepancies included lack of protective screens, poorly maintained screens, and screens permitting excessive velocity that could result in impingement of larvae or small fish. A conclusion from these surveys is that if adequate protection for fish is to exist, screens for water withdrawals need to be properly installed, inspected, and maintained. (PDF file contains 40 pages.)

Congrid eels of the Eastern Pacific and key to their leptocephali

This study indicates that 13 species of congrid larvae belonging to 8 genera occur in the eastern Pacific. The species are: Ariosoma gilberti; Paraconger californiensis; Paraconger sp.; P. dentatus; Chiloconger labiatus; Taenioconger digueti; T. canabus; Gorgasia punctata; G. obtusa; Gnathophis catalinensis; Hildebrandia nitens; Bathycongrus macrurus; and B. varidens. The morphological and anatomical changes undergone during metamorphosis are useful in the identification of the larvae. Larvae are distributed closer to the coastal waters, and are more common from January to May than from June to December. A key to the larvae was developed based on the myotomal counts, adult vertebral counts, pigmentation patterns, and the nature of the teeth and tail tip to distinguish the genera and species. This study shows that Garman's unidentified larvae, Atopichthys acus and A. cingulus, are two different larval stages of Ariosoma gilberti, and points out that Atopichthys dentatus and A. obtusus belong to Paraconger and Gorgasia, respectively. (PDF file contains 25 pages.)

Ichthyoplankton of the continental shelf near Kodiak Island, Alaska

Eleven ichthyoplankton surveys were conducted (1 in 1972 and 10 between 1977 and 1979) in the northeastern Pacific Ocean over the continental shelf off Kodiak Island, Alaska. In the 677 neuston and 632 bongo tows, eggs or larvae of more than 80 fish taxa were found. They were present in every season and throughout the survey area, although more taxa and more individuals were found in summer than in other seasons. Among the more abundant species were the gadid Theragra chalcogramma and several hexagrammids and pleuronectids. The hexagrammids and several coUids were abundant in the neustonic layer, where they spent close to a year as larvae and prejuvenlles. Although the seasonal and geographic distribution of most taxa was complex, two patterns emerged: Late summer-fall spawners produce demersal eggs and have neustonic larvae that remain pelagic for several months (hexagrammids and some cottlds), and spring-summer spawners have pelagic eggs and larvae that spend several weeks in the plankton but are not closely associated with the surface (Theragra chalcogramma, pleuronectlds). (PDF file contains 95 pages.)

The feeding ecology of some zooplankters that are important prey items of larval fish

Diets of 76 species of fish larvae from most oceans of the world were inventoried on the basis of information in 40 published studies. Although certaln geographlc, size- and taxon-specific patterns were apparent, certain zooplankton taxa appeared in the diets of larvae of a variety of fish species in numerous localities. Included were six genera of calanoid copepods (Acartia, Calanus, Centropages, Paracalanus, Pseudocaianus, Temora), three genera of cyclopoid copepods (Corycaeus, Oilhona, Oncata), harpacticoid copepods, copepod nauplii, tintinoids, cladocerans of the genera Evadne and Podon, barnacle nauplii, gastropod larvae, pteropods of the genus Limacina, and appendicularians. Literature on feeding habits of these zooplankters reveals that most of the copepods are omnivorous, feeding upon both phytoplankton and other zooplankton. Some taxa, such as Calanus, Paracalanus, Pseudocalanus, and copepod nauplii appear to be primarily herbivorous, while others, such as Acartia, Centropages, Temora, and cyclopoids exhibit broad omnivory or carnivory. The noncopepod zooplankters are primarily filter-feeders upon pbytoplankton and/or bacterioplankton. Despite the importance of zooplankters in larval fish food webs, spectic knowledge of the feeding ecology of many taxa is poor. Further, much present knowledge comes only from laboratory investigations that may not accurately portray feeding habits of zooplankters in nature. Lack of knowledge of the feeding ecology of many abundant zooplankters, which are also important in larval fish food webs, precludes realistic understanding of pelagic ecosystem dynamics. (PDF file contains 34 pages.)

Ichthyoplankton survey of the estuarine and inshore waters of the Florida Everglades, May 1971 to February 1972

Quarterly ichthyoplankton sampling was conducted at 16 estuarine and 24 inshore stations along the Florida Everglades from May 1971 to February 1972. The area is one of the most pristine along lhe Florida coast. The survey provided the first comprehensive information on seasonal occurrence, abundance (under 10 m' of surface area), and distribution of fish eggs and larvae in this area. A total of 209,462 fish eggs and 78,865 larvae was collected. Eggs were identified only as fish eggs, but among the larvae, 37 families, 47 genera, and 37 species were identified. Abundance of eggs and larvae, and diversity of larvae, were greatest in the inshore zone. The 10 most abundant fish families which together made up 90.7% of all larvae from the study area were, in descending order of abundance: Clupeidae, Engraulidae, Gobiidae, Sciaenidae, Carangidae, Pomadasyidae, Cynoglossidae, Gerreidae, Triglidae, and Soleidae. Clupeidae, Engraulidae, and Gobiidae made up 59.9% of all larvae. The inshore zone (to a depth of about 10 m) was a spawning ground and nursery for many fishes important to fisheries. The catch of small larvae (<>3.5 mm SL) indicated that most fishes identified from the 10 most abundant families spawned throughout the inshore zone at depths of <> 10 m, but Orthopristis chrysoptera, Gerreidae, and Prionotus spp. spawned at depths > 10 m, with offshore to inshore (eastward) larval transport. Salinity was one of several environmental factors that probably limited the numbers of eggs and larvae in the estuarine zone. Abundance of eggs and larvae at inshore stations was usually as great as, and sometimes greater than, the abundance of eggs and larvae at offshore stations (due west of the Everglades). (PDF file contains 81 pages.)

Development of hexagrammids (Pisces: Scorpaeniformes) in the northeastern Pacific Ocean

Larvae of Oxylebius pictus, Zaniolepis sp., Ophiodon elongatus, Hexagrommos stelleri, H. decagrammus, H. lagocephalus, H. octogrammus, and Pleurogrammus monopterygius are described and illustrated from field collections which were supplemented by laboratory reared specimens of some species. Larvae hatch at a rather large size (3-9 mm), are heavily pigmented, and undergo direct development to an epipelagic prejuvenile stage. Larvae or the five genera are separable on the basis of body shape, pigmentation, and meristic characters. Larvae or the four species of Hexagrammos, which are quite similar in appearance, are separable on the basis of a combination of several pigmentation characters. Developmental evidence indicates that Oxylebius and Zaniolepis are similar to each other and are more similar to presumed primitive coUids than the other included genera. Ophiodon is dissimilar to the other four genera. Pleurogrammus and Hexagrommos have similar appearing larvae. Among the species of Hexagrammos a progression or increasing larval pigmentation can be seen from H. stelleri to H. decagrammus, H. lagocephalus, and H. octogrammus. (PDF file contains 50 pages.)

Miscellaneous translations on oyster biology (contents page only - individual articles held as separate documents)

This is a translation of selected articles from the Japanese language publication Hiroshimaken Suisan Shikenjo Hokoku (Report of Hirshima Prefectural Fisheries Experimental Station), Hiroshima City, Japan, vol.22, no. 1, 1960, pages 1-76. Articles translated are: Haematological study of bacteria affected oysters, The distribution of oyster larvae and spatfalls in the Hiroshima City perimeter, On the investigation of the timing of spatfalls, On the prediction of oyster seeding at inner Hiroshima Bay, Oyster growth and its environment at the oyster farm in Hiroshima Bay

Mögliche Ursachen des geringen Heringsnachwuchses in der Nordsee

Though the stocks of North Sea herring seemed to have recovered from small numbers since the mid-1990s we do recently observe a new decline in the spawning stock biomass. This is mainly caused by four consecutive years of small reproduction. Whilst the adults produce enough eggs and larvae only few survive until mature stages. The reasons for the bad recruitment are not clear. In this paper we investigate the influence of climate conditions, in particular the North Atlantic Oscillation (NAO) that obviously triggers the interaction between the size of the spawning stock and the abundance of larvae. We show that approximately 60 % of the recruitment variance can be explained by specific constellations of spawning stock size and climatic conditions. Beside physical factors we also discuss several working hypotheses shedding light on the influence of biological variables on the fluctuation of herring offspring.

Miesmuschel-Langleinenkulturen – Vom wissenschaft-lichen Experiment zur wirtschaftlichen Umsetzung

The development of longline cultures for blue mussels (Mytilus edulis) at the German North Sea coast has been under way since 2001. It has turned out to be a successful and innovative method for the rearing of seeding mussels. The comparison of different tested longline types has proved that single longtubes carrying net collectors are the most stable system given the dynamic conditions in the Jade. Artificial collectors were settled by a large number of mussel larvae. Important settling took place between May and July, with 11 000 to 64 000 individuals per meter collector. The shell length of suspended mussels increased in their first summer at an average of 1.2 mm per week. Between the end of August until the end of September a mean of 2 to 9 kg mussels per meter equalling 4500 to 20 300 individuals per meter were harvested. Relayed on bottom cul-tures the mussel seed continued to grow and could be marketed as consumption mussels after their second summer.

Fischlarven der westlichen Ostsee – Biodiversitätsuntersuchungen von 2000 bis 2005

Fish larvae surveys provide information on the species composition in an area of investigation and leads to a better understanding of the entire fish community. Since 2000 every year in April/May an ichthyoplankton survey in ICES-Subdivision 22 and 24 has been performed to sample the plankton community in the western Baltic Sea. One objective was to acquire indicators of possible changes in the natural structures of the fish community. The time series derived from the Bongo-Net samples is too short to show a trend in larval densities. Up to now samples in the western Baltic Sea yielded only low mean densities. According to the reproductive biology the fish species were divided in three major groups: -Fish species with a long developmental phase in the plankton community -Small short living species with benthic eggs and a reduced planktonic phase -Guests without local spawning populations Species were identified, which were absent in the plankton of the western Baltic Sea in the 1960s and 1970s.

Untersuchungen zur chemischen Zusammensetzung und Nematodenbelastung von Stinten (Osmerus eperlanus L.)

Smelt (Osmerus eperlanus L.) from the river Elbe has a long tradition as local food speciality. It is offered baked or fried every year during spring in many restaurants along the river. Information about the composition of the edible part and its changes during fishing season are scarce. In earlier days the fish was mostly sold by local fisherman directly after catch. Today the fish is also offered as ungutted fresh fish in ice on the whole sale market. The freshness of this fish has not been studied. Smelt from the river Elbe is known to contain nematode larvae (Pseudoterranova decipiens) in the muscle meat. Actual quantitative data on the abundance and prevalence in the commercially offered ice stored fish are missing.

The distribution, abundance, and ecology of larval tunas from the entrance to the Gulf of California

ENGLISH: This study is based on collections of larvae of Thunnus albacares, Euthynnus llneatus, and Auxis sp. obtained from surface and oblique net tows made during seven cruises, each along a comparable track in the entrance of the Gulf of California and each during a different month. Concomitant measurements of surface temperature, salinity, and zooplankton were made at each of the plankton stations. The catches of larval Auxis sp. were examined by analysis of variance techniques to determine which environmental features were associated with the spawning of this tuna as indicated by the distribution of larvae and to gain some insight into the behavior of the larvae themselves. The testing indicated that the spawning of Auxis sp. varied significantly among the different months of the cruises. The testing also indicated that if the larvae were capable of avoiding the sampling apparatus, this ability was not related to features associated with time of day such as light conditions. The analysis did not detect any change in the vertical distribution of the larvae among the months of the experiment. It was concluded that the larvae did not exhibit a diel vertical movement. The measurements of temperature, salinity, and zooplankton volumes were treated as covariates in the analysis. The surface temperature proved to be a highly important factor in explaining the distribution of larvae, but salinity and zooplankton volumes were not. Catches of Thunnus albaeares and Euthynnus lineatus were rare during the course of the study; these are discussed in qualitative terms with respect to the time of the year and the surface temperature. The distribution of larval tunas in the area of study was compared with the distribution of surface water masses. It appeared that these masses had no influence per se on the distribution of larvae. SPANISH: Este estudio está basado en las recolecciones de larvas de Thunnus albacares, Eutbynnus lineatus, y Auxis sp. obtenidas según los arrastres superficiales y oblicuos de la red, realizados durante siete cruceros, cada uno a la entrada del Golfo de California a lo largo de un derrotero comparable, y cada uno durante distintos meses. Las mediciones correspondientes de la temperatura superficial, salinidad y de zooplancton se realizaron en cada una de las estaciones de plancton. Las capturas de larvas Auxís sp. fueron examinadas mediante el análisis de la varianza para determinar cuales características ambientales se encontraban asociadas con el desove de este atún según lo indicaba la distribución de las larvas, y para obtener alguna idea del comportamiento de las larvas en sí mismas. Las pruebas indicaron que el desove de Auxis sp. varió significativamente entre los diferentes meses de los cruceros; indicaron también que si las larvas eran capaces de evitar el aparato de muestreo, esta habilidad no se relacionaba a las características asociadas con la hora del día de acuerdo a las condiciones de luz. El análisis no demostró ningún cambio en la distribución vertical de las larvas durante los meses del experimento. Se determinó que las larvas no exhiben un movimiento vertical diario. Las mediciones de temperatura, salinidad, y de los volúmenes de zooplancton fueron tratadas como covariables en el análisis. La temperatura superficial demostró ser un factor altamente importante en la explicación de la distribución de las larvas, pero la salinidad y los volúmenes de zooplancton no lo fueron. Las capturas de Thunnus albacares y Eutbynnus lineatus fueron pocas durante el curso de este estudio; éstas se discuten en términos cualitativos respecto a la época del año y a la temperatura superficial. La distribución de los atunes larvales en el área de estudio fue comparada con la distribución de las masas superficiales de agua. Parece que estas masas no tienen influencia per se en la distribución de las larvas. (PDF contains 40 pages.)

Guter Nachwuchsjahrgang 2004 des Herings der westlichen Ostsee, des Kattegats und Skagerraks (ICES-Gebiete IIIa und 22 – 24)

Several fishery independent estimates of the year-class strength are necessary for the assessment and the ma-nagement of the total fish stock. An index for the year-class strength of the spring spawning herring in the western Baltic Sea is estimated on the basis of larvae surveys in the most important spawning ground. The results indicate a good year-class 2004.

Evaluierung der historischen Daten der deutschen Larvensurveys im Hauptlaichgebiet des Herings der westlichen Ostsee

The results of the time series of larvae surveys in the main spawning area of the western Baltic Sea spring spawning herring were evaluated. The quality of the recruitment index N 30 was studied. The raw data of 1977 to 1987 have got lost. In 1988 and 1989 the data for the estimation of the recruitment index are biased. Only since 1990 the basic data can be considered reliable.