Number Of Fish Individuals Research Articles

Abundance, Species Diversity, and Conservation Status of Reef Fishes in Dumanquillas Bay, Zamboanga, Philippines

Zamboanga is one of the significant fishing grounds in the Mindanao Region, but little is known about the conservation status of reef fishes, particularly in Dumanquillas Bay, Zamboanga. Thus, this study assessed the abundance, species diversity, and conservation status of reef fishes in the bay. The assessment was conducted within eight sampling stations from May 6 to May 16, 2014. Reef fishes were censused using a line-intercept method. Fourteen thousand fifty individuals and 140 fish species belonging to 30 families were recorded―dominated by the family Pomacentridae. The number of fish individuals was significantly more abundant in Triton Island Station than in other sampling stations, while Muyong Island has the most diverse reef fishes. Almost all species are classified as the least concern category, except for Plectropomus areolatus of Cabog Island, which is under the vulnerable (VU) category. The number of less-valued species was higher than the commercially high-valued species. Therefore, it may indicate the overharvest of the latter group of species. This comprehensive study on reef fishes in Dumangquillas Bay may serve as a reference for fisheries resource management planning or for drafting fisheries policies in the bay.

Fish Community Structure in River Ossiomo, Niger Delta, Nigeria in Relation to Some Selected Environmental Variables

In the past decade, it has been reported that water quality of rivers are deteriorating increasingly. In this study we examined the state of River Ossiomo to assess the current health of the river for a period of 24 months from April 2019 to March 2020, then July 2020 to May 2021 in three well marked out stations. The study was to determine the relationship between environmental variables and fish species assemblage in the river. From the results of the physico-chemical variables, the mean values of pollution indicating physico-chemical variables such as sulphate (1.26+0.32mg/l) and total suspended solids (TSS) (5.53+1.89mg/l) were higher in station 2. On the other hand, pH (5.94+0.48), DO (8.64+1.57mg/l), turbidity (7.48+7.63NTU), TDS (29.64+14.65mg/l) and phosphate (0.43+0.31mg/l) mean values were highest in station 1. Conductivity (70.87+26.42µS/cm) and nitrate (0.49+0.34mg/l) mean values were highest in station 3. Further, dissolved oxygen (DO) was higher in station 1, the reference station. The analysis of variance (ANOVA), we performed for the physico-chemical variables revealed that temperature, conductivity, DO, total dissolved solids (TDS), alkalinity, TSS, sulphate, phosphate and nitrate were significantly different among the three stations sampled (P<0.05), while pH, BOD and turbidity were not significant among the three stations sampled (P>0.05). The result of the principal component analysis showed that conductivity was positively associated with station 3, and temperature, TDS and alkalinity were negatively associated with stations 1 and 2. A total of 2,324 fish individuals belonging to 29 taxa were recorded in the entire study period. Station 1 harbours more fish species (1018), followed by station 2 (809), and we recorded the lowest number of fish individuals in station 3 (497). Auchenoglanis occidentalis was the most preponderant fish species probably occasioned by its level of adaptation to prevailing environmental conditions in the study river. The least abundant fish species was Synodontis eupterus.The canonical correspondence analysis we used in visualizing the relationship between fish species and physico-chemical variables showed that fish taxa such as Distichodus brevipinni, Cteropoma kinsleyae, Tilapia zillii, Malapterarus electricus, Mormyrus engystoma, and Synodontis nigita that were positively associated with pollution indicating physico-chemical variables were suggested as indicators for monitoring riverine health in the Niger Delta area of Nigeria. We recommend that more detailed studies should be carried out in River Ossiomo to confirm this result. However, this study serves as a baseline study in the present study area.

Fishes: The Forgotten Sentient Beings

Fish – these four letters stand for an enormous number of trillions of animals but still up to the present day we only know little about their inner life. There have been numerous studies showing impressively that they indeed feel pain. Even though they lack a human-like neocortex, apparently other parts of the fish brain seem to be responsible for processing emotions and consciousness. Observations from nature strongly support the remarkable capacity of fishes to live a conscious life: they have an excellent memory and use land marks for orientation, recognize the different individuals in their shoal and remember their hierarchical status in the group. They cooperate between species and even invent interspecific sign language. In conclusion, there is clear evidence that fishes are conscious, sentient beings – and indeed since 2009 they are recognized as such by the EU in article 13 TFEU. However, under welfare aspects of secondary EU legislation, the fishes are either only included on a very basic general level or not considered at all. Especially considering the numbers of fish individuals and the methods used in fisheries and aquaculture, it is high time to overcome this erroneous view and to finally grant them the protection they deserve as ‘sentient beings’ – on the legislative level, but also in fisheries and aquaculture practices, policies, and not least in our daily behaviour.

Fish Diversity, Ecological Status, and Conservation Measures of the Coastal Waters in Tubay, Agusan del Norte, Philippines

This study was conducted primarily to determine fish diversity of the coastal waters of mining areas in Tubay, Agusan del Norte. There were 23 fish species identified belonging to 19 genera and 12 families. Indo-pacific sergeant fish ( Abudefduf vaigiensis) was relatively the most abundant in all the three stations comprising more than 25% of the total. Station 1 had the most numerous (556) and diverse (1.969) fish species. There was a significant difference in the number of fish individuals but had no significant difference on species diversity index with respect to sampling stations. Station 2 had the highest species richness index (0.633), while Station 3 had the most even distribution (0.817). Stations 1 and 2 were 77.8% similar. The average water depth, temperature, transparency, pH and salinity were 4.52 meters, 26.53 ÂoC, 3.97 meters, 8 and 34.33 ppt, respectively. These all fall within the DENR standards for Class SC water. Â Keywords - Fish diversity, properties, conservation, coastal waters

Fish‐based assessment of ecological status of Finnish lakes loaded by diffuse nutrient pollution from agriculture

Abstract The European Union Water Framework Directive stipulates that pressures on surface waters due to diffuse loading of nutrients have to be taken into account in determination of their ecological status. A Finnish data set of fish communities in 178 lakes was used to assess the effects of agriculture‐induced nutrient loads on the ecological status of lakes. The lakes were divided to reference (n = 100) and impacted sites (n = 78) based on water quality, land use and nutrient load data. Fish sampling was conducted by standardised gill net test fishing. A fish‐based classification tool of the four parameters (EQR4) was applied to assess the ecological status of lakes. The parameters included were: mean total biomass of fish per gill net night, number of fish individuals per gill net night, biomass proportion of cyprinid fishes and the presence of indicator species. The analysis resulted in a median EQR4 value of 0.78 (good status) for reference lakes and 0.56 (moderate status) for affected lakes. Thus, the classification tool gave an acceptable output for different nutrient‐loaded lakes.

Factors affecting distribution and abundance of small demersal fishes in the Gulf of Carpentaria, Australia

The distribution and abundance of small demersal fishes at depths of 7 to 63 m in the Gulf of Carpentaria were surveyed at 103 stations in 1990 and 60 stations in 1991 with the aid of a Church dredge. A total of 234 species from 70 families was recorded. The most abundant fish groups were cryptic or benthic species such as pleuronectiforms, scorpaenids, apogonids, platycephalids, monacanthids and gobiids. Several species, such as Elates ransonnetti, Pseudorhombus elevatus and Suggrundus macracanthus, are widely distributed; others had a narrower distribution. Apogon poecilopterus, Apogon fasciatus, Arnoglossus waitei and Uranoscopus cognatus were most abundant in the northern Gulf of Carpentaria and Cynoglossus macrophthalmus, Dactyloptena papilio and Paramonacanthus japonicus in the eastern gulf. The dredge is more efficient at catching smaller fish: the smallest individuals of 113 species were caught by the dredge and a further 32 small species were caught only by the dredge. The effects of depth, substratum type and turbidity on the abundance of 17 common species at different stations are described. Neither temperature nor salinity showed significant correlations with catches of the common species. There were significant correlations between the presence of structured benthos and both the number of fish species and the number of fish individuals. The relationship between benthic structure and fish is discussed in relation to the possible effects of trawling, and it is postulated that changes to structure resulting from trawling may affect fish community composition.

サケ・マス流網の投揚網時刻と魚群の羅網との関係

For enlightening the efficiency of drift net operation in salmon fishery, some available data of catches of red salmon, chum salmon and pink salmon were schematized as stated below and looked at from new angles independent of the extreme divergency of their actual catches: 1. According to the number of fish individuals actually caught in every one of 12 sections constituting a stretch of drift net and differing inevitably from section to section as regards the times of laying out and hauling up, daily ranks of catches were decided for each one of these sections of net as well as for each one of said kinds of salmons. From the daily ranks the corresponding averages of daily ranks, the average daily ranks so to speak, were further calculated in proportion to the days on which the drift net was actually operated and divided into 2 groups, one higher and the other lower than the mean of ranks 12-1, viz., 6.5. These groups were marked with ?? and ??, respectively, and entered in panes of a rectangular chart on the co-ordinates of which the times of day of laying out and hauling up of net-sections were graduated. Similar types of charts were prepared for the avearge daily ranks for (i) the whole interval of fishing season from June to August, (ii) the catches in June and July, respectively, (iii) the cases in which the sum of caught individuals of red salmon and chum salmon was greater and smaller, respectively, as compared with those of pink salmon and (iv) the cases in which big catches and small catches of said three kinds of salmon were respectively experienced (Figs. 1, 2 and 3). 2. Comparing between the charts the kind of marks of said two groups, or in other words, examining whether the marks in corresponding panes are concordant or discordant with each other, efficiency of catching chum salmon may be said to be likely bound up with the times of day at which a drift net is laid out and hauled up (Figs. 2, b)-g) and Table 1), while any positive rule can hardly be found as for efficient catches of red salmon and pink salmon (Figs. 1, b)-g), 3, b)-g) and Table 1). 3. According as the average daily ranks above and below 6.5 assigned to the panes in Figs. 1-3, b)-g) were predominant at least 3 times over each other, three charts carrying the panes marked with ?? and ?? were prepared for visualizing the times of day of effective catches of chum salmon (Fig. 4, a)), red salmon (Fig. 4, b)) and pink salmon (Fig. 4. c)). On the basis of Figs. 4, a)-c), it may be said that chum salmon and pink salmon are caught most effectively by keeping the net laid out rather for a long and a short time, respectively, while any positive comment is difficult to be made upon the time of effective catch of red salmon. The fact that effective duration of drift net operation varies according to the species of salmon to be caught seems to be explained to some degree from the ecology of the fish in question, Thus pink salmon, being small in size, may perhaps be liable to get out of the net in which it became once entangled so that the apparently strange situation is met with that an effective catch of this fish is realized with a net kept laid out rather for a short time. Actually observed body portion by which the different kinds of salmons are held entrapped (Table 2) suggests that these fishes differ likely from one another also in regard to the tendency of getting out of the net. 4. From many assumed types of catch in which a fish may visit a drift net and fall entangled therein, the types indicated in Figs. 5, a) and b) were picked up as bearing closest resemblances to those in Fig. 2, a) and Fig. 1, a) respectively.