Department of Zoology, Wildlife
and Fisheries, University of Agriculture, Faisalabad.
Fishery is the most important economic activity in the villages and towns along
the coast; it is the sole source of employment and income generationAccording to
the latest estimates, the total area covered by fish ponds is about 60 500 ha (Sindh,
49 170 ha; Punjab, 10 500 ha; NWFP, 560 ha; and the other provinces (Balochistan,
Azad Jammu Kashmir and Northern Area), 240 ha). About 13 000 fish farms have so
far been established across Pakistan, varying considerably in size. The
fisheries sector contributes around 1% to the GDP of Pakistan. . Global recorded
fish production was 82.6 million tonnes in 2011 and 79.7 million tonnes in 2012.
The fraction of assessed stocks fished within biologically sustainable levels
has exhibited a decreasing trend, declining from 90 percent in 1974 to 71.2
percent in 2011. Recent government data reported that Pakistan’s total fish
production for 2006-07 was about 590,000 metric tonnes where 400,000 metric
tonnes came from marine resources whereas 190,000 metric tonnes were produced
from inland resources including aquaculture. There are 531 species of Fish in
Pakistan. 233 of them are of fresh water. Mahseer is the national fish of
Pakistan.
During the last several decades, anthropogenic activities such as environmental
deterioration, overexploitation, hydrological alterations, and inappropriate
stocking practices have negatively influenced the fisheries resources at various
levels. Genetic monitoring is imperative to understand captive breeding systems,
to detect the geographical structure of genetic diversity and to underpin the
factors contributing to fitness of species. Humans-induced pollution, siltation
due to deforestation, loss of nursing and breeding points, disturbance in the
migration ways and careless capturing of brooders in breeding season, contribute
to decline in wild fish populations. Overfishing is the main factor behind
declining fish stocks and degraded fish habitats and threatened productivity of
aquatic biodiversity hotspots, making them more vulnerable to climate change.
Furthermore, global ecological changes, such as warming and shifts in
precipitation, nitrogen deposition, and runoff patterns are superimposed upon
these threats. Habitat alteration contributed to 71% of extinctions, overfishing
contributed to 29%, and pollution contributed to 26%. More than 70 % of the
world’s fisheries are under the stress of ‘significantly depleted’, ‘over
exploited’ and the rest are ‘fully exploited’.
The predictable consequences of inadequately managed breeding programme are loss
of diversity and outbreeding depression. Hatchery stocks of fish and captivity
bred animals have association with depressed performance, survival and
reproduction. Individual decreases the fitness due to these losses, during the
expression of inbreeding depression. These losses increase in the number of
alleles within individuals and also decreasing the effective population size (Ne).
Use of small number of brood fish generation after generation may lead to reduce
genetic variability and indiscriminant hybridization causes loss of genetic
purity of the species.
To sustain the diversity of fish populations, it is compulsory to take into
account their natural breeding systems. The factors that diminish the effective
size of population size (Ne) are population history, high reproductive variation
among individuals, sex-ratio biases, harem formation and inbreeding. Smaller
populations are more vulnerable to increase selfing, random genetic drift and
mating among related organisms. Moreover, the mating system may not only be
affected by genetic exchange among populations but also between generations.
Allelic differences among geographically isolated groups can identify prolific
source populations and isolated sink populations and allow investigation of
subpopulation relatedness and invasion pathways. Additionally, inferences based
on traditional ecological studies and genetic approaches can be combined to
inform predictive demographic models.
Dispersal of individuals may be conditioned by life-history and behavioural
traits, as well as by geographical barriers imposed by the geomorphology of a
given area. This is particularly relevant in freshwater fishes. However,
geomorphology may not always remain stable throughout evolutionary time, and
physical changes in the landscape may markedly influence dispersal and thus gene
flow rates, affecting the degree of among-population divergence. Genetic drift
and reduced dispersal would cause a continuous loss of the heterozygosity within
respective colonies and a simultaneous increase in their differences. The
consequence of drift and dispersal along with the metapopualtion events are
responsible for the reduction of total diversity. Frequent local extinction and
recolonization actions would result in loss of difference within and between
populations.
High levels of management, husbandry and rigorous assays for testing culture
performance are the major factors for the improvement of genetic work which
requires very good facilities for the segregation of fish stock from each other
and from wild fish stock. High fecundity and fastest generation times are the
significant traits for the improvement in the fish genetics. Recognization and
the administration of the genetic diversity is imperative within the species
because the breeding and selection of desired traits can lead to enhancement in
the frequency of that attribute for the economic, social or cultural value
within the particular species.
So, there should be a need of essential management measures to achieve the
provisions of fisheries of Pakistan including the existence of an aquaculture
policy, aquaculture development plan and regulations to support the policy and
to enhance mechanisms to improve the implementation of the institutional
frameworks. There should be established a reference framework for national and
international efforts for the formulation of policies and other legal and
institutional frameworks and instruments, to ensure sustainable fish production.
In addition, there is a section to assess the capacity of States to develop
knowledge, information, technology and advice in support of the actions at
public as well as universities levels.