Multidisciplinary approach to sea lion population status management
Full Solution
Alice Masper
This solution utilizes former information and personal data to create a data base to characterize the most important environmental and anthropogenic factors that affect the fitness of California sea lion rookeries. This includes modelling how environmental factors influence historical colony trends, mapping sources of contamination around the colony, mapping the fishing areas as well as collecting available information about California sea lion diseases.
Last update: 28 Mar 2019
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Context
Challenges addressed
Guide and support governmental authorities to improve in conservation planning decisions and enhance collaboration among research community members, governmental authorities and local population, particularly fishing community.
Location
Sonora, Mexico
North America
Process
Summary of the process
In addition to provide a valuation of how environmental factors force abundance and recruitment of sea lions, Building Block 1 can also be regarded as a robust screening method to come up with a set of relevant parameters analyzed afterwards in a multivariate scheme, Building Block 2. Together, both Blocks will serve to evaluate the different status of rookeries and identify the areas with priority of management intervention.
Building Blocks
Population trend and environmental influence model
This building block is very useful to understand the population trend and how environmental factors take a part and influence this tendency.
Modification and adaptation of existing population models which describe trends as well as the relationship between the parental stock size and newborns make it possible to understand how the environment influences sea lion population growth rates and abundance. These model approach helps to understand whether a given sea lion population is influenced or not by environmental variables. The approach ultimately allows deciding if one or several sea lion populations could be good indicators of environmental change.
Enabling factors
1. Information about population: total number of individuals; numbers of pups; numbers of females.
2. Availability of environmental variables. All the time series of environmental variables were fetched from internet specialized public sites.
Lesson learned
Developing these models helped me to understand that population trend is a very complex phenomenon:
-It could be not directly related with the population trend but could work in synergy with other events.
-El Niño event isn’t the only or main event that influences the population trend and recruitment process.
- Not all the colonies are influenced by the same environmental change; a few are not responsive of the variables tested.
- The environmental conditions seem to influence more the survival rates than fecundity.
It is very important to have sufficient information about population and apply the rates of other similar animals just in extreme necessity because these trends are very specific for species.
Multifactor diagnostic chart
This building block helps to identify the factors that threaten sea lion populations with a spatially-explicit, multifactorial approach. The outcome is a set of prescribed actions for each population in the same geographic realm, depending on their diagnostic characteristics, avoiding an “all-purpose” general, possibly ineffective solution.
For each colony or population of sea lions, a set of environmental factors is selected and described with a historical perspective. Examples of relevant factors are: sea temperature, upwelling index, pH, chlorophyll, diet composition of sea lions, microbial load, heavy metals. Next, a group of drivers are identified as influencing the region of interest and for a given year, their influence in factors is determined and qualified. Drivers can be: ENSO, climate change, over-fishing, pollution. The end result could be that only a few or several colonies could be affected, even in the same geographical region or sub-region.
Enabling factors
1. Information about population: total number of individuals; numbers of pups; numbers of females, diet information for sea lions, pollution data.
2. Availability of environmental variables. All the time series of environmental variables were fetched from internet specialized public sites.
Lesson learned
Because this Building Block requires a fair amount of data, some basic information might not be available. At the end, using a data-poor approach, one has to use a set of available environmental variables, namely temperature, chlorophyll and upwelling.
Impacts
1. Models have been developed which indicate a strong relationship between environmental variables and population trends and parent-pup relationships
2. Active collaboration with federal government environmental authority PROFEPA and veterinary Elsa Coria Galindo demonstrates how we can collaborate, in this case, to rescue carcasses for necropsy and adequate removal of remains to guarantee health of costal area.
3. Participation in governmental authority CONANP activities: California sea lions’ population monitoring and local community raising awareness.
Beneficiaries
- Governmental authorities: modulate the management effort
- Researchers: facility to obtain information and create collaboration with researcher from different area
- Local populations: possibility to mitigate the fishing competence with sea lion
Story
When I started to study Gulf of California sea lion population, I was fascinated by the complexity of their spatial population dynamics. Suddenly I noticed that each colony, despite the closeness, had different biological characteristics. Actually the population is a union of four subpopulations that live in different environmental conditions and have diverse alimentary and behavioral habits. So I thought that natural environmental and anthropogenic variables should have different impact in the diverse colonies. These differences can explain the different response in populations’ trend and vulnerability of colonies, so I’ve started to investigate this relationship. Despite the quite abundant information available about population, the information is so fragmented and disperses that I needed to collect historical and actual data. So, by means of the project it will be possible to utilize and value decades of research coming from different disciplines to evaluate, in a multidisciplinary approach, the status and trend of California sea lion populations. Finally, the data collection might be shared among other researches in order to: - simplify data research - inspire new areas of investigation - foster networking
