7 research outputs found
Biology, Fishery, Conservation and Management of Indian Ocean Tuna Fisheries
The focus of the study is to explore the recent trend
of the world tuna fishery with special reference to the Indian Ocean
tuna fisheries and its conservation and sustainable management.
In the Indian Ocean, tuna catches have increased rapidly from
about 179959 t in 1980 to about 832246 t in 1995. They have
continued to increase up to 2005; the catch that year was 1201465
t, forming about 26% of the world catch. Since 2006 onwards
there has been a decline in the volume of catches and in 2008
the catch was only 913625 t. The Principal species caught in the
Indian Ocean are skipjack and yellowfin. Western Indian Ocean
contributed 78.2% and eastern Indian Ocean 21.8% of the total
tuna production from the Indian Ocean. The Indian Ocean stock
is currently overfished and IOTC has made some recommendations
for management regulations aimed at sustaining the tuna stock.
Fishing operations can cause ecological impacts of different types:
by catches, damage of the habitat, mortalities caused by lost or
discarded gear, pollution, generation of marine debris, etc. Periodic
reassessment of the tuna potential is also required with adequate
inputs from exploratory surveys as well as commercial landings
and this may prevent any unsustainable trends in the development
of the tuna fishing industry in the Indian Ocean
Efficient distinction of invasive aquatic plant species from non-invasive related species using DNA barcoding
Biological invasions are regarded as threats to global biodiversity. Among invasive aliens, a number of plant species belonging to the genera Myriophyllum, Ludwigia and Cabomba, and to the Hydrocharitaceae family pose a particular ecological threat to water bodies. Therefore, one would try to prevent them from entering a country. However, many related species are commercially traded, and distinguishing invasive from non-invasive species based on morphology alone is often difficult for plants in a vegetative stage. In this regard, DNA barcoding could become a good alternative. In this study, 242 samples belonging to 26 species from 10 genera of aquatic plants were assessed using the chloroplast loci trnH-psbA, matK and rbcL. Despite testing a large number of primer sets and several PCR protocols, the matK locus could not be amplified or sequenced reliably and therefore was left out of the analysis. Using the other two loci, eight invasive species could be distinguished from their respective related species, a ninth one failed to produce sequences of sufficient quality. Based on the criteria of universal application, high sequence divergence and level of species discrimination, the trnH-psbA noncoding spacer was the best performing barcode in the aquatic plant species studied. Thus, DNA barcoding may be helpful with enforcing a ban on trade of such invasive species, such as is already in place in the Netherlands. This will become even more so once DNA barcoding would be turned into machinery routinely operable by a nonspecialist in botany and molecular genetics