Number Of Fish Larvae Research Articles

The influence of the Black Sea rim current and the coastal quasi-stationary anticyclonic Eddie on the distribution of ichthyoplankton and jellyfish

This article describes the Black Sea quasi-stationary coastal anticyclonic eddy (CAE), with large accumulations of zooplankton and ichthyoplankton, which were registered in August 2021 off the northeastern Black Sea during the period of a tropical-type atmospheric mesocyclone. Intense rains (60–80 millimeters of precipitation) caused flooding and large volumes of terrestrial water entered the sea. Water flows came from rivers into the coastal area and flowed into the CAEs. As a result, there were favorable conditions for the growth of plankton, fish eggs and, larvae. Thus, in the Sochi CAE, against the background of a high concentration of chlorophyll a, and the abundance of small-sized fractions of the fodder zooplankton, there was an almost 30-fold increase in the number of fish larvae (947 ind.·m−2 in the CAE and 33.5 ind.·m−2 in the surrounding waters) and the accumulation of jellyfish Aurelia aurita (Linnaeus, 1758), which is their food competitor, with an abundance of up to 44 ind.·m−2. The data obtained indicates that the Black Sea coastal quasi-stationary anticyclones arise between the cyclonic rim current (Main Black Sea current) and the coast, which can be of great importance in the formation of fish abundance.

Tidal Variations of Fish Larvae Measured Using a 15-Day Continuous Ichthyoplankton Survey in Subei Shoal: Management Implications for the Red-Crowned Crane (Grus japonensis) Population in Yancheng Nature Reserve.

The National Yancheng Rare Birds Nature Reserve is a vitally important staging habitat for the wild population of red-crowned cranes (Grus japonensis) in China. The population relies on local high-protein food sources, such as fish juveniles, to fuel their migratory journeys. However, little is known about the ecology of the fish larvae and juveniles that migrate to the inshore area via tidal rhythm in Subei Shoal, which is adjacent to the reserve. Therefore, we used a fixed study station (32°55'1.2″ N, 121°19'58.8″ E) to conduct a continuous 15-day ichthyoplankton survey at 2 h intervals beginning at 05:00 on 25 April and ending at 03:00 on 10 May 2019. We identified the tidal variations in the number of fish larvae and juveniles and the number at various developmental stages and assessed how they were related to environmental variables such as sea surface temperature, salinity, turbidity, and tidal height in the Dafeng Sea area of Subei Shoal. We found that the number of species and larval individuals were highest and lowest, respectively, at the highest and lowest tidal height, and they obviously increased and decreased with the rising and ebb tide, respectively. Our findings indicate that the variation in numbers of the larvae and juveniles depends on species and developmental stage. The species Acanthogobius ommaturus, Pholis fangi, Cynoglossus joyneri, Liza haematocheila, and Lateolabrax japonicus and the total number of larvae were most influenced by tidal height. These results provide a better understanding of the habitat of prey species of the red-crowned crane wild population as well as scientific data that can be applied to manage the wild population in the reserve sustainably.

Seagrass and rhodolith beds are important seascapes for the development of fish eggs and larvae in tropical coastal areas

In this study, the ichthyoplankton in two distinct tropical seascapes, gravelly sand with rhodolith beds (SRB) and muddy sand with seagrasses, were compared. The number of eggs was higher in the seagrass beds; however, the number of fish larvae was slightly higher in the SRB. Seagrass beds present less turbulent hydrodynamics and favor the retention of eggs and spawning. A more structured habitat provides better shelter, especially for eggs. However, as ontogeny progresses, the fish can explore areas with less shelter. This behavior was observed in this study, where the less structured SRB habitat had a high density of larvae in the later developmental stage. The dominance of earlier larval stages demonstrates a preference for more protected and less turbulent seascapes for nursery and offspring rearing. The results highlight that mapping of these seascapes (e.g., seagrass and rhodolith beds) will help to establish conservation measures to protect ecological connectivity and important tropical species.

Fish spawning strategies in the northwestern Mediterranean Sea

The Mediterranean is globally considered an oligotrophic sea. However, there are some places or certain seasons in which mechanisms that enhance fertility may occur. These mechanisms, and related processes, are especially relevant in maintaining fish populations when they take place during the period of larval development. This contribution analyzes how environmental conditions occurring in the NW Mediterranean, at local and seasonal scales, determine the temporal and spatial patterns of fish reproductive activity in the region. The structure of the bathymetry, diversity of adult fish habitats and hydrodynamic mechanisms conditioning the primary production of the region (e.g., shelf-slope density front and associated current, continental water inflows, winter mixing, stratification of the water column) determine the location of spawning and the distribution patterns of fish eggs and larvae. A pronounced seasonal variability regarding both the number of species and the number of fish larvae in the plankton can be observed throughout the year. Most NW Mediterranean fish reproduce during the spring–summer stratification period, when the phytoplankton biomass values at the upper layers of the water column are lower than in winter. The development of the Deep Chlorophyll Maximum in this period and the high zooplankton biomass associated to it offers an important food source for the larvae. Additionally, during this period the inputs of continental waters are one of the fertilization mechanisms of surface waters and some species, as anchovy, takes advantage of this situation. Autumn–winter is the period with lower ichthyoplankton diversity, being dominated by sardine. Vertical mixing during winter is one of the mechanisms that enhance productivity. Overall, fish species show reproductive strategies and larval fish behavior that allow them to take advantage of the available resources throughout the seasonal cycle. These strategies, together with the high ecological efficiency of oligotrophic systems, contribute to the relatively high yield of Mediterranean fisheries. In a context of global change, understanding of the mechanisms relating environmental changes to the extent of spatial and temporal location of suitable spawning habitats of fish is a key first step to predicting and projecting such future changes, and thereby adapting to these changes.

ОЦЕНКА ЧИСЛЕННОСТИ РАННЕЙ МОЛОДИ РЫБ НА ПРИБРЕЖНЫХ НЕРЕСТИЛИЩАХ МЕШИНСКОГО ЗАЛИВА КУЙБЫШЕВСКОГО ВОДОХРАНИЛИЩА

The results of six-year observations (2012-2017) in the Meshinsky Gulf of the Kuibyshev reservoir concerning the evaluation of the reproduction efficiency of the main commercial fish of this section of the reservoir have been reviewed and analyzed. Data are given on the species composition of prolarvae and larvae of fish in the coastal part of the reservoir. It has been established that the most abundant in the studied years was the fry of roach, bream and silver bream; the larvae of carp and ruff were least common in catches. A method for estimating yields by catches of fish larvae based on deviations in the mean value of the catch has been proposed. According to these data, in 2012-2017 there was one high-yielding generation, in the remaining years - medium-yielding. It is shown that the dynamics of the number of fish larvae in the coastal region depends on the course of spawning and obeys the normal distribution in time. Analysis of the relative indices of the quantity of larvae - pieces/catches and pieces/1m of the coastal area in the studied years has been given. A method is described for calculating the absolute abundance of fish larvae in the littoral by the example of the Meshinsky Gulf. According to calculated data, the average number of early juveniles in the littoral of the Meshinsky Gulf in 2012-2017 was about 4 billion specimens, which corresponds to the figures obtained in previous years in the Sviyazhsky Gulf of the Kuibyshev Reservoir. The study results have great practical importance and can serve as data for prediction of catches and determining the state of ecological system of the reservoir.

Individual-specific transgenerational marking of common carp Cyprinus carpio, L., using 86Sr/84Sr double spikes

Transgenerational isotopic marking has been recognised as an efficient tool for mass marking of high numbers of fish larvae by injecting female spawners with enriched isotope solutions. So far, mainly enriched stable barium isotopes have been applied for this purpose. Here, we present an alternative approach for individual-specific transgenerational marking using strontium 86Sr/84Sr double spikes. Four isotonic double-spike solutions with different molar fractions of 86Sr and 84Sr and different total Sr concentrations were administered to four female spawners of common carp, Cyprinus carpio, L., by intraperitoneal injection, and one additional female spawner was injected a blank isotonic solution as control. Otoliths (lapilli) were sampled from juvenile offspring and analysed for their Sr isotopic composition by laser ablation–multi collector–inductively coupled plasma–mass spectrometry. Central otolith regions of the progeny of female carps treated with concentrations of at least 0.45 mg 84Sr kg–1 bodyweight and 2.28 mg 86Sr kg–1 bodyweight showed a significant shift of the absolute 88Sr/86Sr and 88Sr/84Sr isotope ratios from the natural baseline. Isotope pattern deconvolution was successfully applied for the identification of the originally injected 86Sr/84Sr molar fraction ratios of the individual double spikes. Enriched stable Sr isotope double spikes represent an important alternative to enriched stable Ba isotopes for transgenerational marking, especially in freshwater systems.

Kelimpahan Larva Ikan Pada Kondisi Air Pasang Dan Surut Di Muara Sungai Pilang Sari, Desa Pidodo Kulon, Kendal <br><i>[Abundance Of Fish Larvae In Neap And Tide Condition In Estuary Of Pilang Sari River, Pidodo Kulon Village, Kendal ]<i>

Abstract The aim of this research is to know the abundance of fish larvae in neap and tide condition in estuary of Pilang Sari river, Pidodo Kulon village, Kendal. This research is case study where the fish larvae that been caught was deeply observed in the limited time, place and population. Sample was taken in the three place. Data were collected used seine net when the neap and tide of sea level. The number of fish larva that been caught during the research are 12.983. Including from 8 genus are Stolephorus, Ambassis, Periapthalmus, Gerres, Leiognathus, Terapon, Atherinomarus. The composition of fish larvae that been caught when neap and tide was dominated by Stolephorus and Ambassis. When the new moon phase, the number of fish larvae that been caught is 1151, quarter moon is 2379, full moon is 5243 and three–quarters of the moon is 4110 fish larvae. The result of this research shows the relationship between the pattern of tide and amount of the fish larvae that been caught every moon phase. In the sping tide pattern, amount of the fish larvae that been caught was bigger than neap tide pattern. In commonly, fish larvae that been caught when the tide is bigger than abundance of fish larva that caught when the water was neap.

Physical and biological processes controlling the distribution of fish larvae in the NW Mediterranean

The Mediterranean is globally considered an oligotrophic sea. However, there are some places or certain seasons in which mechanisms that enhance fertility may occur. These mechanisms and related processes are especially relevant when they take place during the period of larval development. This study analyzes how environmental conditions occurring in the NW Mediterranean, at local and seasonal scales, contribute to determine the temporal and spatial patterns of fish reproductive activity in the region. The structure of the bathymetry, types of bottoms, diversity of adult fish habitats, as well as mechanisms conditioning the primary production of the region determine the location of spawning, whereas physical processes (e.g., shelf-slope density front and associated current, continental water inflows, winter mixing, stratification of the water column) determine the final distribution patterns of fish eggs and larvae. High larval concentrations occur over the edge of the continental shelf in relation to the presence of the shelf-slope front and its associated convergence. However, this pattern is subject to considerable spatio-temporal variability, due to frontal mesoscale activity. High larval abundance can also be observed near the coast in zones with topographic irregularities that can greatly modify circulation favouring penetration of slope waters into the shelf. Finally, larvae of large pelagic migratory species are mainly distributed in areas under the influence of recent Atlantic Water (AW) and near the frontal system between these inflowing AW and the more saline waters of the northern basin. A pronounced seasonal variability regarding both the number of species and the number of fish larvae in the plankton can be observed throughout the year. The two dominant species, sardine and anchovy, have non-overlapping spawning periods, autumn–winter and spring–summer, respectively. The diversity of feeding patterns as well as the fact that different fish species have different spawning periods might reduce inter- and intra-specific competition for food resources in this area. Most NW Mediterranean fish reproduce during the spring–summer stratification period, when the phytoplankton biomass values at the upper layers of the water column are lower than in winter. The development of the Deep Chlorophyll Maximum in this period and the high zooplankton biomass associated to it offers an important food source for the larvae. Additionally, during this period the inputs of continental waters in certain areas are one of the fertilization mechanisms of surface waters and some species, as anchovy, takes advantage of this situation. Autumn–winter is the period with lower ichthyoplankton diversity, being dominated by sardine, which reproduces on the continental shelf. The mixing of the water column during winter is one of the mechanisms that enhances productivity on continental shelves. Moreover, there are no intense currents on the shelf and the circulation is usually anticyclonic, favouring larval retention in this zone. Fish species show reproductive strategies and larval fish behaviour that allow them to take advantage of the available resources throughout the seasonal cycle. These strategies, together with the high ecological efficiency of oligotrophic systems, contribute to the relatively high yield of Mediterranean fisheries.

Plankton studies in Buzzards Bay, Massachusetts, USA. V. Ichthyoplankton, 1987 to 1993

Monthly sampling for ichthyoplankton was conducted at 8 stations in Buzzards Bay, Massachusetts, from October 1987 to September 1993 using a 48 cm diameter plankton net with 0.102 mm mesh. From October 1992 to September 1993, an additional 75 cm diameter net with 0.202 mm mesh was also towed to compare mesh selectivity. Stations included two with heavy anthropogenic impact, the urbanized inner harbor of New Bedford, Massachusetts, and over New Bedford's offshore sewage outfall, as well as other nearshore shallow and offshore deep stations in comparatively pristine areas of the bay. Fish larvae from 32 genera were identified. Fish eggs were counted but not identified. There was a pronounced summer peak in larval abundance dominated by cunner Tautogolabrus adspersus, anchovy Anchoa sp. and tautog Tautoga onitis. A smaller winter/ early spring peak was dominated by sand lance Ammodytes sp. This pattern was evident for all 6 years of the study. The assemblage of fish larvae found in Buzzards Bay differed from that in Cape Cod Bay, lending support to the concept of Cape Cod as a faunal boundary. The 2 differently sized nets used during the last year of the study did not catch significantly different numbers of fish larvae per m 3 , but length frequency distributions of 4 abundant species of larvae revealed that the smaller mesh net caught significantly smaller Anchoa sp. The larger mesh net collected significantly more species of fish larvae. A comparison of annual mean catches of 4 species did not reveal significant changes in abundance over 6 yr.

The Ichthyoplankton of Selected Estuaries in Sarawak and Sabah: Composition, Distribution and Habitat Affinities

The ichthyoplankton assemblages of 23 estuaries in Sarawak and Sabah were surveyed with particular reference to the culturally and commercially important clupeidTenualosa toli. The species composition, distribution and density of all fish larvae were recorded, together with the physical characteristics of each estuary. A more detailed study was made of the Lupar and Lassa estuaries, which are the ‘core area’ forT. toli.The estuaries fall into two groups. The first consists of the estuaries of the ‘core area’ from the Sebako in the west to the Lassa in the east, and the Labuk and Kinabatangan estuaries of eastern Sabah. They are large and deep, have middle-range salinities with no halocline, are highly turbid and have tidal ranges of >3·5m and strong currents. There is little seasonal change in freshwater input and their waters are not peat-stained. Their total zooplankton biomasses (approximately 0·05gm−3dry weight, excluding fish larvae) are an order of magnitude greater than biomasses in the second group of estuaries. The second group consists of all estuaries east of the Lassa as far as the Papar in Sabah. They are mostly smaller, shallower and have more variable salinities than the ‘core area’ estuaries, with marked haloclines and seasonal changes in freshwater inflow, lower turbidities, weaker currents, tidal ranges of <2m and low overall zooplankton biomasses.The composition of the ichthyoplankton is different in these two groups of estuaries. The assemblage in the first group (‘core area’) of estuaries consists primarily of taxa associated with estuarine and/or turbid water conditions, whereas those in the smaller estuaries of the second group have mainly marine and clearer water affinities. Only the Gobiidae are ubiquitous. Very few larvae of freshwater species were recorded in any of the estuaries. The number of fish larvae was highly variable, but the mean densities (0·01–9·23m−3) were similar, and similarly variable, to the densities reported for other tropical estuaries.The diversity of the ichthyoplankton assemblage in Sarawak and Sabah estuaries (56 taxa, 26 families) is lower than in most other tropical estuaries of the Indo-west Pacific. This is possibly because of their rigorous physical nature, particularly the very high turbidities and current speeds, or in smaller, less physically rigorous estuaries, the low biomass of zooplankton available as food for the larvae.

Downstream Transport of Fish Larvae in a Shallow Prairie River

Abstract Ichthyoplankton drift samples from the lower James River, South Dakota, during the 1978 spring and summer, were composed of 16 taxa representing six families. The predominant taxa were freshwater drum Aplodinotus grunniens, gizzard shad Dorosoma cepedianum, Catostomidae, Cyprinidae, Ictaluridae, and Centrarchidae in decreasing order of abundance. Peak drift densities (460/1,000 m3) occurred on July 6 when the predominant ichthyoplankters were larval freshwater drums (323/1,000 m3) and gizzard shad (58/1,000 m3). The average weekly number of fish larvae moving through the study area was approximately 2.52 million. Collectively, the lower James River ichthyoplankton exhibited no significant diel periodicity, but four taxa did so. Gizzard shad, ictalurids, and catostomids were nocturnal drifters; their densities began increasing at dusk, peaked at 0100 hours, and subsequently declined at 0500 hours. Larval freshwater drums were diurnal drifters; greatest densities occurred between 0900 and 1700 hour...

Error Bounds for Estimates of Entrained Ichthyoplankton

Entrainment of fish larvae and eggs was monitored at the J. H. Campbell Plant, eastern Lake Michigan, from 1977 to 1979. A procedure for calculating error bounds for estimated number of fish larvae (or eggs) entrained by the plant for each year of operation, assuming independence among observations, was outlined. A new method for calculating these bounds was devised by adjusting the variance for its non-independent component, using time series analysis. Serial correlation in the data was accounted for by modeling the sequence of entrainment data for a year as a time series. For many taxa of fish larvae the entrainment observations were determined to be independent and no adjustment was necessary. The width of the adjusted error-bound intervals ranged from 4.8 to 87.9% greater than unadjusted ones for those taxa for which adjustment was required, thus assuming independence among observations could result in serious underestimation of the error-bound interval.Key words: error bounds, variance, entrainment, Lake Michigan, serial correlation, time series analysis

The development of the stomach in clarias lazera and the intestinal absorption of protein macromolecules.

The development of the stomach of the teleost, Clarias lazera, during the early posthatching period, is described, and the developing stomach is compared with that of adult Clarias. The stomach develops in two distinct parts: the corpus, which differentiates first, and the pylorus. The corpus contains a mucous surface epithelium, arranged in folds, and a tubular gland system containing only one type of gland cell, to which the secretion of pepsinogen and HCl is attributed. The pyloric region does not contain tubular glands. From the ultrastructure of the gland cells, the 3H-thymidine labeling index, and the onset of acid production (as determined with pH indicators) it is concluded that a functional stomach is present in juveniles with a standard length of +/- 11 mm (approximately 12 days after fertilization at 23-24 degrees C). The ultrastructure of the intestinal epithelium has also been studied. The intestine consists of three segments, similar to those described for stomachless teleosts and a number of fish larvae. In larvae as well as in juveniles, the enterocytes of the second segment show pinocytosis of horseradish peroxidase, although in the juveniles the stomach has already developed. This second segment has the same relative length in all studied larvae and juveniles and is also present in adult Clarias. It is therefore concluded that the capacity to absorb protein macromolecules is not specifically related to the absence of a functional stomach in this teleost species.

Relacion standing crop zooplanctonico y densidad de larvas de peces en Bahia de Concepcion, Chile

From monthly zooplankton samples collected during October 1976 to October 1977, the seasonal variation of zooplankton standing crop and its relation to the number offish larvae from Bay of Concepcion has been established. The zooplankton standing crop varied between 58 ml/m2 in August and 430 ml/m2 in January. The number offish larvae in the same sample ranged from 30 larvae /m2 in January to 1045 larvae/m2 in March. An inverse relationship between the zooplankton standing crop and the number of fish larvae it was checked and this relation is discussed according to the bibliographic antecedents.

Miniature Aquarium System for Rearing Small Numbers of Fish Larvae

Abstract Eggs of 19 species of river fish were hatched and the larvae reared in small aquariums flushed with swimming-pool water. The simple construction of the aquarium system kept costs low and allowed the use of simplified feeding methods. Size and structure of the system can easily be altered to meet changing needs.

稚魚網による炉水量および採集量の変動について

The present study's objective has been to clarify the tow to tow variations in the number of fish larvae taken in relation to the variation of the volume of water filtered. More than 230 surface towings and 170 towings of subsurface layers were carried out in the regions off central and southern Japan, and the results obtained are as follows: (1) Volume of water filtered vary from tow to tow, net to net and it is difficult to keep the volume of water filtered to a constant level by only maintaining a constant ship speed and towing time. (2) Collecting efficiency both in number and size appeared better in small meshed nets than large meshed nets at sea areas of poor plankton. However, the difference in the numbers collected diminished at towings in rich plankton waters, and the variation in collection became large with small meshed nets. (3) Variations in collection was large for samples of low collection and this decreased by increasing the amount of collection in numbers. (4) Movement of net during towing was stable at shallow layers and at calm seas and it oscillated to some extent at deeper layers and seas having complexed water stratification.