The Chondrichthyans Research Group, called CONDROS (www.condros.com.ar), was created in 2007 as a part of the Ictiological Resource Lab in the Institute of Marine Biology and Fisheries Alte. Storni (IBMP Alte Storni), San Antonio Oeste, Río Negro, Argentina. The main objective of the group is the study of the biology, ecology, behaviour and reproducitve patterns of sharks, rays and chimaeras to preserve and manage this resource.
In 1999 the Fishing Committee of FAO creates the International Action Plan for the conservation and management of sharks in the world (IAP - Sharks). The main objective of this plan is to preserve the shark species from overfishing (directly or by by-catch). From this international plan new local plans were created and executed in each country, including Argentina in 2009. Between the main objectives of this plan are determine critical areas, protect sharks biodiversity and the function and structure of the ecosystem. Today, the main difficult that faced biologists and stakeholders to manage and preserve sharks and rays species and their populations in the world is the lack of ecological information, work tools and political will. In Argentina, while many species continue to show strong evidences of decline (e.g. tope shark Galeorhinus galeus, sand-tiger Carcharias taurus, copper Carcharhinus brachyurus, angel sharks Squatina spp. and some skates' species) non-evaluated management actions have been adopted to remediate these trends, despite the official implementation of the National Plan of Action for Sharks in 2009.
The scientific output of this project is the recording of ecological data of threatened shark species such as habitat uses, vertical movements and regional migrations. Afterwards, we will create a GIS database as a new conservation tool to improve the local management and conservation of elasmobranches in the South West Atlantic.
The tope shark is a coastal transient species, critically endangered in the South West Atlantic. Tope sharks probably migrate from southern Brazil to northern Patagonia during spring comprising a single population across Argentina, Uruguay and Brazil. Due to the large numbers of school sharks congregated during spring and summer in closed gulfs and bays of northern Patagonia these are considered the main nursery areas for the species (e.g. inshore embayments of Bahia San Blas).
First PSAT tagging in Argentina
Tope shark individuals were captured, tagged using a MK10 satellite pop-up archival transmitting (PSAT) in Bahia Anegada (Natural Reserve of Bahia San Blas, Northern Patagonia). Three of them were tagged during November 2011 and two during November 2012 with the logistic support of local sportive anglers. Each individual was captured with sportive fishing gear, identified, measured for total length, sexed and tagged. Three PSAT tags were inserted intramuscularly with a dart and two tags were secured at the base of the first dorsal fin with a plastic cattle identification tag. Data collection frequency was set to every 5 seconds with tags programmed to record water temperature, depth and light level binned into 6 hours histograms for 180 and 210 days. The automatic release feature was enabled with tags regarding depth variations ±3 m for 48 hours as constant depth. Igor Pro Version 6.2 (WaveMetrics, Inc.) and the Data Analysis Program 3.0 (Wildlife Computers) were used to analyze shark swimming data. Vertical movements were examined by plotting the depth and temperature readings for sharks against time of day and constructing a depth and temperature profile for each tracking period.
Depth behavior of tope sharks
Five females of tope shark from 120 to 140 cm total length were captured, tagged and released. The first three tags detached prematurely between 8 and 21 days and two of them were physically recovered, full archival datasets from 696 hours were downloaded with a total tracked period of 40 days. The other two tags are still collecting data. The largest distance travelled from the deployment position was 51.2 km and all sharks tagged offs were inside the reserve. Tope sharks demonstrated a narrow vertical distribution, inhabiting depths from the surface to a maximum of 24.5 m, but without a clear diel vertical pattern. The most common dive trend observed was vertical oscillatory movements. Sharks spent most of the time during day (80%) and night (83%) at depths shallower than 10 meters and the rest of the time between 10 and 20 m. Tope sharks used to swim mainly in waters within temperature between 17°C and 19°C, and in a minor percentage in temperatures between 19°C and 21°C. Maximum vertical speeds and dive heights were recorded at night and overall ascents movements were higher than descents.
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Project 11252181 location - Argentina, South America