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SEAPODYM
Climate Profiles
• IPSL CMIP4 Climate Change Model (future)
– Simulations for SKJ, BET, ALB
– Extraction of EEZ level information
– Published on SPC website
• Historical period
– More detailed examination how climate impact
tuna distributions at EEZ scale
– Web tool for profiles and data extraction
Climate Change
• IPSL CMIP 4 model has following biases
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equatorial upwelling poorly placed.
Convergence zones dynamics poorly replicated
warm pool temperatures depressed.
ENSO period incorrect
• No perfect ocean model that replicates
everything
• Developed a new physical forcing which is an
ensemble of the best performing ocean models
www.spc.int/ofp/seapodym
Data Query Tool
Marshall Islands Skipjack Profile
Climate versus Fishing Influences
Changes in tuna distribution and abundance of skipjack tuna may lead to changes in fishery distribution and catch rates which could have potential impacts on
Pacific economies, food security and social capital. The strong interaction between environment and tuna species, necessitates the inclusion of climate
variability in tuna fisheries management to assure their sustainable exploitation. Here we profile the skipjack resources in the Marshall Islands using the
SEAPODYM model (Omega v1.0 optimisation) for the period 2003-2012.
The influence of fishing on the skipjack biomass estimated in the Marshall Island was small (Figure 1). There is some minor influence on the estimate of adult
biomass with on average a 3 % decline due to historical fishing. We did not estimate any effect of fishing on the biomass of young skipjack or upon larvae.
The spatial distribution of the depletion of adult skipjack biomass is principally restricted to the southern sector of the EEZ (Figure 2). The largest influence on
biomasses are environmental however these remain small. Adult biomasses were estimated to vary by 30%, young skipjack by 45% and larvae by 21% over
the model period of 2003-2012.
The model estimates do not demonstrate any seasonal patterns in depletion. The
seasonality estimated in skipjack biomass was minor but the peaks differed
between the cohorts (Figure 3). Adult biomasses are highest in April/May and
lowest in December with abundance varying by approximately 15000 mt over
the year. Young skipjack have a similar trend with a peak abundance in June and
low abundance in December with abundance varying by approximately 4000 mt
over the year. The number of larvae varies by 100000 over the year with larvae
abundance peaking in September and at its minima in March.
The time series is insufficient in length to draw conclusion about the influence of
ENSO on skipjack abundance in the Marshall Islands. A general declining trend in
abundance of adult and young is evident (Figure 3). The low adult abundances
observed in the summer of 2005/2006 and 2007/2008 and 2011/2012 coincide
with La Nina events. The low abundance in mid 2009 coincide with the
commencement of an El Nino event. The peaks in young skipjack observed in
mid 2007 and quarter 3 of 2010 coincide with the commencement of 2 La Nina
events. The peaks in larvae abundance in the first quarter of 2007, and last
quarter of 2009 coincide with end of El Nino events. The peak in the third
quarter of 2011 coincides with the commencement of a La Nina event. The
period of low abundance in the first half of 2008 coincides with a La Nina event.
The distribution of adult and young skipjack is strongly influenced by the dynamic changes in
available habitat. On average the abundance of skipjack is typically higher in latitudes greater
than 10 degrees than those in the equator in each quarter (Figure 4 a and b). However the
variability in distribution of abundance is high with areas of high abundance changing between
equatorial and more temperate regions on a monthly basis as food and oceanographic
condition change (Figure 5). Abundance in the tropical latitudes is influenced by the position
of the convergence zone between the warm-pool cold tongue ecosystems (generate Figure 6
showing abundance and boundary (salinity or temp). In the higher latitudes abundance is
influenced by forage availability and larger skipjack that are less prevalent in the purse-seine
catch (need to check this).
Spawning habitat (Figure 4 c) is strongly associated with sea surface temperatures with
spawning habitat found in the equatorial latitudes. Monthly variation is spawning in the
equatorial region is influenced by primary productivity (generate the last figure showing larvae
and PP association).
Summary
• Tools to make the information from SEAPODYM
easily available to SPC members
• Improved the capability for climate change
simulations and subsequent risk evaluations
• Provided training opportunities
• Oceanography summaries
• Accessible through multiple sources on SPC web
– www.spc.int/ofp/seapodym
– www.spc.int/OFPMemberCountries
– www.spc.int/en/our-work/climate-change