Page 41 - climate-change2013

5. Migration changes

Evidence from regional studies of climate change ef-
fects have shown that some migrant species are shift-
ing their migration departure time, the route they take
or the time of their arrival in their wintering or breeding
grounds (UNEP-CMS, 2006). Discrepancies between Illustrations: J. da Cuña Sanchez
the new times of arrival or breeding and the availability
of food supplies could have important consequences Tursiops truncatus was found to shift from coastal to
for the productivity and abundance of these popula- open waters in some areas during the abnormal tem-
tions or their prey. peratures recorded in 2003. Similar observations could
give an idea about changes in their migration pat-
Long-term data can reveal trends in the spring or au- terns. Oceanographic variation associated with climate
tumn arrival dates of these migratory species in MPAs. change (e.g. temperature anomalies, stronger thermal
stratification or differences in nutrient loads) can affect
INDICATOR the abundance and distribution of prey species, pro-
ducing a mismatch that may lead cetaceans to choose
Recorded arrival dates different habitats and feeding strategies in order to
adapt to the new conditions.
of migratory species
PROPOSED MONITORING PROCEDURE
Analysis of long-term data can reveal timing shifts in MPA managers could select a number of migrant spe-
selected species. Some large migratory fish species cies that are common in their areas and keep a record
are already responding to warming (Bombace, 2001). of their spring or autumn arrival dates. Suitable species
A well-documented example is the time when bluefin could be the fin whale Balaenoptera physalus, striped
tuna Thunnus thynnus and amberjack Seriola dumer- dolphin Stenella coeruleoalba and bottlenose dolphin
ilii in the northern and central Mediterranean return to Tursiops truncatus. Alternatively, specific campaigns
their winter territories, which has shifted from autumn could be organized annually to search for the selected
to mid-winter (Bombace, 2001). Spawning condition is species and estimate their abundance.
also closely correlated with water temperature.
Local fishermen or other stakeholder groups might also
Migratory changes could in turn affect the productivity be able to contribute invaluable information on trends in
of these populations and the livelihoods of the fishing migratory fish of commercial importance (such as Sphy-
communities depending on them. raena viridensis, Caranx crysos, Sparisoma cretense,
Coryphaena hippurus, Seriola dumerili and Balistes ca-
In the case of most marine mammals, their distribution, priscus), particularly to estimate their abundance (e.g.
abundance and migration are strongly influenced by by counts of fish caught) and the timing of fish availabil-
prey availability. The habitat of the bottlenose dolphin ity in or close to MPAs.

Thunnus thynnus. Photo: K. Ellenbogen, OCEANA

MEDITERRANEAN MARINE PROTECTED AREAS AND CLIMATE CHANGE: A GUIDE TO REGIONAL MONITORING AND ADAPTATION OPPORTUNITIES 39