MigraMar relies on several cutting-edge technologies to achieve our scientific and conservation goals:
- To assess the spatial and temporal behavior of migratory marine species.
- To assess the spatial and temporal trends in abundance, size structure and biomass productivity of migratory marine species.
- To assess the behavior and population dynamic response of marine migratory species to changes in the oceanographic setting, particularly in awe of strong environmental events such as ENSO and long-term climate change scenarios.
- To assess the genetic diversity, gene flow and effective population size between marine species (sub) populations living within the MPAs under assessment.
Research methods Spatial and temporal behavior
Satellite Tagging is used to evaluate spatial behavior of fish, turtles, and marine mammals in areas of known aggregation within MPAs as well as national and international waters between them. There are several tag types that are used within the scope of our project: i) tags that are affixed to the fin of a shark (via bolt and nuts or fin clamps), ii) tags that freely float but are affixed via a tether nylon line and an anchoring device (place inside the individual’s muscle over the dorsal area), iii) tags that are affixed to the dorsal area (via suction cups or percutaneous); and iv) tags that are attached into the hard or soft shells in turtles.
Acoustic tagging is used to assess the fine-scale habitat use and connectivity of marine species throughout the ETP region. It uses acoustic devices that emit a coded sound signal to passively track a marine animal whenever it passes by receiver stations that are permanently listening for the coded signals. Marine animals are fitted with coded VEMCO V16-6H tags (diameter 16mm, length 95mm). These tags can be either tethered to a stainless-steel dart with stainless steel wire and be placed by using a pole spear while free diving, or be surgically implanted in the abdominal cavity of fish.
To passively track all tagged individuals, MigraMar has an array of receivers located all around the Eastern Pacific Ocean. This array is mostly comprised by VEMCO VR2W receivers set at 30 m deep and anchored to concrete blocks by PVC coated marine stainless-steel cable ropes. In some deep-sea areas, VEMCO VRAR underwater acoustic receivers are in place. The detection range of these receiver was previously estimated to vary from a distance of 200 to 300 m. Our array of receivers and the data we are continuously collecting are constantly uploaded to the Ocean Tracking Network portal.
Spatial and temporal abundance trends
The baited remote underwater video (BRUVs) technique is used to assess abundance, size structure and biomass of pelagic marine species. A stereo BRUVs consist in two front facing cameras placed in an angle of 8 degree which are used to create a three-dimensional (stereo) image, which is later used to measure any object (or fish) that passes in front of the cameras. A BRUV set has three to five 3D stations place in parallel resembling a longline fishing gear. While BRUVs use bait to attract fish with the smell, it replaces hooks from longlines for the 3D camera systems. This makes it a not invasive assessing technique in comparison to experimental fishing. Also, our BRUVs systems are coupled with a central 360 camera to allow observing animals passing by all angles and reduce biased associated to counting individuals while watching a reduced field of view.
BRUVs deployment is generally done near seamounts and in open waters inside and outside MPAs. BRUVs are allowing MigraMar to assess previously unknown seamounts outside MPAs, such as around the Cocos, Galapagos, Coiba and Malpelo region.
Underwater visuals surveys (UVS) are used to estimate the relative abundance of marine megafauna species within and around MPAs. Two divers counting all the animals that passed by in a 30-minute period carry this out. The census begins at 25 m and ends at 15 m depth ascending gradually during this time. At the same time the current strength and visibility are estimated, water temperature and thermocline are measured.
Photo-identification is used to identify unique individuals visiting a study area and estimate true population size. To achieve this, calculations are made based on the sighting of new and resighting of previously known individuals. Photos are taken of the left-hand cephalic-branchial area of whale sharks and manta rays, and of the tail and dorsal area of whale and dolphins encountered during the trip. These photos are submitted to world databases that store and compare data on marine megafauna sightings and identities. For example, whale shark data is constantly uploaded into the ECOCEAN whale shark global data bank (www.whaleshark.org). The photos are also distributed to all the institutions participating for the compilation of local data banks.
Species response to the environment
To assess the behavior and population dynamic response of marine migratory species to changes in the oceanographic setting, remote sensing data matched with behavioral and population dynamics data is used. Oceanographic variables that has been considered or in use are sea surface temperature (hereafter SST) obtained from the NOAA’s Optimum Interpolated Sea Surface Temperature, the SST from the EU Copernicus Marine Service Global Ocean Physics Reanalysis; Chlorophyll a data from the Moderate Resolution Imaging Spectroradiometer (Modis)-Aqua satellites, Chlorophyll a from the EU Copernicus Marine Service Global Ocean Chlorophyl; the mixed layer density from the EU Copernicus Marine Service Global Ocean Physics Reanalysis, and the eddy kinetic energy (hereafter EKE) derived from the TOPEX ⁄ Poseidon and ERS-2 altimeters. The EKE is a measure of the energy associated with the turbulent flow of the ocean.
Genetic diversity, gene flow and effective population
To assess the genetic diversity, gene flow and effective population size between marine species (sub) populations living within the MPAs under assessment, DNA tissue collection are carried out. This activity was developed with the aim of building on the pre-existing fish, reptiles and marine mammals genetic sample collections that already exists in the region. A Hawaiian sling spear, pneumatic launcher, and crossbows with a modified biopsy tip that is designed to extract the smallest possible amount of tissue from the skin of the fish or mammal is used. The samples will be labelled and preserved in alcohol.
Furthermore, to assess the diversity of marine species populations living within and beyond MPAs, environmental DNA (eDNA) collection are carried out. Water samples are collected and preserved in Niskin crystal water bottles to preserve DNA fragments left by fish and marine species found in the area. The eDNA is a genetic tool developed to assess the species richness of an area based on traces of DNA of a species left behind when swimming freely. The use of eDNA could increase the probability of detecting species that other methods cannot detect.
Animal Ethics: taking care of nature
All the research carried out by MigraMar follows the United States and Australian codes on human and animal experimentation. Our research methods have been reviewed and approved in the past by the Animal Care and Use Committee of the University of California – Davis; and the Safety, Ethics and Institutional Biosafety Committees of the University of Tasmania. Currently, we operate under guidelines of the Galapagos National Park Directorate animal welfare regulations; the Ministry of Environment and Sustainable Development through the Natural National Parks of Colombia; the Ministry of Environment of Panamá; and the Ministry of Environment of Costa Rica.