Environmental Engineering Reference
In-Depth Information
term environmental variability and forcing (Hutchings and Myers 1993,
Marteinsdottir and Steinarsson 1998, Hsieh et al. 2006).
Through the social learning, the individuals use information provided
by others to make decisions related to feeding, mating, habitat selection
for spawning or migrating (Brown and Laland 2003, Planque et al. 2010),
thus the loss of older individuals by fi shing could affect their behavioral
and migration pattern (Corten 2002, Petitgas et al. 2006, Planque et al.
2010). What is more, they transmit their knowledge on migration and
location of suitable habitat of spawning to the younger fi shes (Warner
1988, Corten 2002). If the older individuals are removed, it could derivate
in a loss of tradition and it is possible that they would never recover their
migration pattern (Planque et al. 2010). The spatial distribution of fi shes
is also conditioned by the range and abundance of a population. These
two characteristics are directly linked so if the abundance falls the range
distribution of the population will contract (MacCall 1990, Fisher and Frank
2004). At low population abundance, the population has a tendency to
inhabit only the most suitable spaces (hot spots), reducing its encountering
rate with prey and competitive species, thus benefi ting the development
of other populations less impacted by fi shing (Planque et al. 2010).
The ecological consequences of overfi shing leads to a reduction of the
top-down predatory control, and bottom-up processes are expected to play
a relatively more important role in the dynamics of marine communities.
The predominance of bottom-up processes suggests that climate variability
will have a greater impact on the structure of these communities, leading
to population instability and shifts in the community structure (Perry et
al. 2010b, Planque et al. 2010).
To conclude, it is worth to highlight that heavy fi shing not only reduces
population's levels, it also modifi es the age structure and the geographical
distribution. As a result, the population is less resilient to unfavorable
environmental conditions (Brander 2005, Brander 2010, Planque et al.
2010).
How Climate Change is Affecting and Will Affect World
Fisheries
In the marine systems the environmental conditions play a major role in
the distribution of fi sh populations. The climate change, which leads to an
increase of sea water temperature and an alteration of ocean currents and
coastal upwelling patterns, is producing a change in the distribution of the
pelagic species. The situation is further impaired by overfi shing, which
affects the resilience of fi sh communities and ultimately leads to ecosystem
degradation. As a result, climate change will have a large impact on the
