A comparative study on the effectiveness of gillnet and longline fishing methods used by multi-day fishermen in Matara fisheries district
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Date
2015
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
The fisheries sector of Sri Lanka is a primary source of animal protein production. According to the
high rate of population growth in Sri Lanka, fish food demand is increasing. To fulfill this increasing
demand, there should be an effective fishing method for high rate of exploitation and exploited
resources should be high quality and high value for the better utilization. In the late 1980s, Sri Lankan
state introduced multiday offshore fishing vessels for the development of Sri Lankan offshore
fisheries (Kariyawasam, 2010). The gillnet fishery and the longline fishery is the common fishing
methods used in the deep sea fishing in Sri Lanka. According to the DFAR statistics in 2013, Matara
fisheries district is one of the districts which provide high fish production to the nation. The gillnet
fishery is most commonly used fishing method in multiday boats fishermen in Matara fisheries
district and they do not engage in longline fishery very much. The identification of the suitable fishing
methods is important to increase production level, quality of the production and income of the
multiday fishermen. Therefore the present study is focused on comparison of the effectiveness of
gillnet fishing and longline fishing methods as a deep sea fishing method used by multiday fishermen
in Matara district.
Materials and Methodology
The data were collected from multiday fishing boats in “Dondra” fisheries harbor from 1 of May to
14 of June 2014. The sample size was determined by “Moving average method” and the total
landings and fishing methods of 66 multiday boats were collected accordingly. Catch and effort data,
income of the fishermen and quality of the landing were collected using prepared data sheets. The
catch and effort data collection sheet was consisted of data regarding the duration of the fishing, the
fishing techniques (gear) used in the trip, total catch per day, the species composition of the catch in
number and/ or weight, gear information (length of net, mesh size, number of hooks per long line,
soaking time,) vessel information (storage facilities, hauling technique, length of boats). The income
data collection sheet was consisted of species composition, total weight of each fish species and price
of the fish in particular day. Organoleptic survey has been done in order to determine the quality of
the fish yield of each boat. According to the organoleptic evaluation, nature of the fish skin, nature
of the gill, eye appearance and consistency of flesh were evaluated. The quality of the fish has been
evaluated by scoring them according to the level of quality. Then mean of the score of the quality
parameter was calculated to determine quality of the harvest in each multi-day boat. The collected
data have been analyzed by using “Microsoft excel-2010” and compared with “One-way ANOVA
table” by using “Minitab 16” software.
Results and Discussion
According to the study, there were 3 types of main fishing methods which were used by multi-day
fishermen in Matara fisheries district. They are, gillnet, longline and combination of gillnet and
longline fishing methods. There were 39.4% multiday fishing boats which used only gill net, 22.7%
multiday fishing boats which used only long line and 37.8% fishing boats which used a combination
of gillnet and long line. Mainly tuna and tuna like species were targeted in the study. The total catches
of the different fishing gears were taken as weight of harvest per boat day. According to the results,
the mean catch per boat day of the gill net, long line and combination of the longline and gill net were
133.7 kg, 94.2 kg, and 165.1 kg respectively. Therefore the multiday boats which used combination
of gillnet and longline fishing method gained significantly higher yield than that of gillnet and
longline fishing methods. The lower mean catch per boat day was gained by the longline fishing
method.
When considering main fish species which were caught by each fishing gear, the mean catches per
boat day of Skipjack tuna (Katsuwonus pelamis) were 62.11 kg, and 64.76 kg respectively for gill
net, and combination of the gill net and longline. In Matara fisheries district there were no multiday
fishermen who used longline fishing method to catch skipjack tuna. The mean catches per boat day
for yellow fin tuna (Thunnus albacares) were 7.05 kg, 79.39 kg and 70.56 kg respectively for gillnet,
longline and combination of gillnet and long line. Similarly the mean catches per boat day of frigate
tuna (Auxis thazard) were 12.29 kg, and 70.56 kg in gillnet, and combination of gillnet and longline
respectively. There was no frigate tuna catch in long line fishery. According to this result, mainly
long line fishing gear was used to harvest yellow fin tuna. The skipjack tuna and frigate tuna were
harvested by using gillnet fishing method.
When considering income of the multiday fishermen, the mean of the total income of multi-day
fishermen who harvested fish using gill net, longline and combination of gillnet and longline is Rs
300,577.00, Rs 1,251,567.00 and Rs 1,068,474.00, respectively. The highest income was gained by
the multi-day fishermen who used longline fishing method and the lowest income was gained by
fishermen who used gillnet fishing method, among the three fishing methods.
According to the organoleptic survey data, the quality of the fish in gill net, long line and combination
of gill net and long line fishing methods were 1.99 0.41,2.32 0.31 and 2.04 0.39,respectively.
The quality of the fish was high in fish which were harvested by longline and quality was low in fish
which were harvested by gillnet.
In the ANOVA test, there was not significant different between gear categories and the total catch
per boat day (P>0.05). But, there was a significant different between gear categories and catch per
boat day of tuna and tuna like species (P<0.05). Similarly, there were significant differences between
gear categories and income of the fishermen and also gear categories and quality of fish (P<0.05).
According to these result, it shows gear categories are not significantly affect on the total catches per
boat day but it significantly affect for the catches of tuna and tuna like species, income of the
fishermen and quality of fish.
According to the above results, the gillnet fishing method has recorded, high catch, low income and
low quality fish and long line fishing method has recorded low catch, high income and high quality
fish while combination of gillnet and long line fishing method has recorded high catch, medium
income and medium quality fish.
But the ANOVA result showed total catch per boat day was not significantly affected by fishing gear
categories. Therefore, though they have similar amount of fish harvest, multi-day boat fishermen who
used longline fishing method has had high income and high quality fish than other two types of
fishing methods. The analysis of catch composition of tuna and tuna like species showed that long
line fishing method is much more species selective fishing gear than other two types of fishing
methods. It is used to catch only target fish species which having high commercial value. And also,
the amount of fish discarded by the longline is less than that of gillnet due to harvest of high quality
fish in longline fishing method. The reason is that the fish remain alive for much longer period when
hooked than when gilled (Santoset al., 2002). Because of that reason, the quality of the fish that
harvested by longline is higher than gillnet fishing method. Because of their high quality, the value
of the fish increases and fishermen obtained higher income with the longline fishing method.
Description
Keywords
Fish, fish Industry, Animal Sciences, Aquaculture and Fisheries, Aquatic Resources