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SOUTHERN RIGHT WHALE, Eubalaena australis: A long term study of the population dynamics and identification of Marine Protected Areas in Uruguay
Costa P.1, 2; Riet-Sapriza F.G.1, 2; Jorge G.T.1,31
Proyecto FRANCAAUSTRAL; 2Cetceos Uruguay; 3Seccin Etologa, Facultad de Ciencias, UdelaR.
Conservation StatusThe Southern right whale (SRW), Eubalaena australis, is considered the rarest of large whales and the population was driven to the edge of extinction during the XVIII and XIX centuries due to the whaling activity (Best & Underhill, 1990; Burnell, 2001). This pressure was too great that by the mid-1840s SRW was considered to be commercially extinct (Stewart & Todd, 2001). Although protected from hunting by international agreement since 1935, the population recovery has been slow (Arias & Harris, 1999; Best et al., 2001; Patenaude & Baker, 2001). However, the SRW is an example of the ability of whale stock to recover from whaling activity increasing at annual rate of 7-8 % (IWC, 2001). The species is currently listed as low risk/ conservation dependant category (IUCN, 2003). This designation implies that southern right whales are showing signs of recovery in some areas, which depends on running conservation programs. If those efforts are interrupted, in a period of five years the species would be changed to the category of threatened species (IUCN, 2003).
DistributionSouthern HemisphereThe SRW is a migratory animal, during the austral summer it is found in high latitudes in its subantarctic feeding sites (60 S). At the beginning of the austral winter it 1
migrates to middle and low latitudes, looking for template and calm waters for mating and calving (Payne, 1976; Whitehead et al., 1986; Payne et al., 1990). Courtship, mating and births occur in shallow bays, being these behaviours easily seen from the shore (Payne, 1986). Important breeding areas includes Peninsula Valds in the South western Atlantic (Payne, 1986; Payne et al., 1990; Bastida & Lichtestein, 1984), South Africa, (Best, 1970, 1981, 1990; Best & Underhill, 1990; Best & Ruther,1992), Tristn da Cunha (Best, 1988), Australia (Bannister, 1990) and New Zealand (Patenaude et al., 1998). Recent research shows that the coasts of Santa Catarina in Brazil are an important breeding and nursing area for SRW (Palazzo & Flores, 1998). Seven feeding grounds are recognised, based on sightings and historical records from commercial hunting (IWC, 2001). One feeding ground extends from Brazil/False to Banks/Malvinas Island in Argentina, considered a corridor offshore Brazil, Uruguay and Argentina, between 30 and 55S and west of 40W (IWC, 2001; Tormosov et al., 1998).
LocalUruguay is situated between the grades 30 and 35 South, between two important SRW reproductive sites: the coasts of Santa Catarina State (27- 25 South, Brazil) and Peninsula Valds (42-43 South, Argentina). The geographic location of Uruguay match with other reproductive sites in the southern hemisphere: South Africa (30-35 S) and The Great Australian Bay (30-35 S). The main characteristic of this area (30S -35S) is being a highly complex hydrographic system due to the convergence of waters from different origins: subantarctic waters from Falklands currents, subtropical waters from Brazilian currents and fluvial waters from La Plata River. This makes the region highly productive due to the flux of nutrients originated at the run-off of La Plata River and the contribution of subantarctic waters from Falklands currents (Gali, 2000). In Uruguay sightings were recorded since the 70s (Mermoz, 1980), with a maximum of 10 individuals in July of 1975, near the coasts of the islands of Cabo Polonio (Costa et al., 2005). Systematic survey from 2001 to 2003 suggested that of the species was conducted along the Uruguayan coast, to assess the status and habitat Uruguayan coast could be an important social grounds (Costa et al., 2007).
Southern right whale biologySpecies Description ReproductionRight whales are slow breeders, females have their first calves around 9 years (Carwardine, 1995; IWC, 2001) and give birth to a single calf every 3 to 5 years (Carwardine, 1995; Kraus & Hatch, 2001). Post-partum ovulation does not appear to occur (Burnell, 2001). The length of gestation is estimated to be between 12 and 13 months (Kraus & Hatch, 2001; Best et al., 2003). Right whales aggregate in large, active groups during which males appear to compete for access to a single female. Interacting groups, which show behavioural events such as tail and flipper slaps, spy hopping and belly up have traditionally been associated with mating groups (Payne, 1986). Hamilton and Mayo (1990), Kraus and Hatch (2001) and Best et al. (2003) defined surface active groups (SAGs) as groups of two or more individuals that interact on the surface, less than one body length apart, in which one focal individual is surrounded by other individuals. The focal animal is usually a mature female surrounded mostly by males (Best et al., 2003). The female often displayed the belly-up event, making copulation difficult and thus inciting males to compete (Cassini & Vila, 1990; Kraus & Hatch, 2001). Males compete at two levels, for access to position next to a female so they can inseminate her, and via sperm competition (Best et al., 2003). Right whales have the largest testes (972kg) and penises (averages 14.3% of their body length) of the baleen whales (Berta & Sumich, 1999; Kraus & Hatch, 2001).
CalfRight whales nurse their calf in template water and protected coast such as bay. At birth calf weight about 3 to 4 tonnes and measure 1/3 to 1/4 of their mother length. The lactation period last one year. Their first migration to the Antarctic occurs when they separate from their mother on their return to breeding and calving sites (Payne, 1986).
Mother give birth every 3 years and have their first calf on average at the age of 8-9 years ( Payne, 1986).
DietPlanktonic food resources in most habitats where right whales are thought to feed are dominated by the calanoid copepods Calanus finmarchicus, Pseudocalanus sp. and Centropages spp. Although a variety of other food organisms including euphausids, swarming galaethiads and colonial siphonophores have occasionally been reported worldwide (Mayo et al., 2001). Right whales feed by skimming the surface of the water collecting prey on the baleen, as water is expelled by the tongue (Berta & Sumich, 1999). This process requires more energy than the whale would expend by swimming with its mouth closed because of the additional drag. The number of copepods consumed per unit time (and hence the amount of energy available in the form of food) varies with the concentration of copepods in the water. The threshold concentration of copepods estimate below which it is not energetically favourable for the whale to feed is 4 x 103 copepods m-3 (Beardsley et al., 1996).
Conservation & ManagementProblems and threatsA. The numbers of whales present in Uruguay before or during the whaling industry is unknown. Furthermore, the records from 1970s and 1990s were occasional and cannot be used to determine population tendencies. For this reason the status of the SRW in our coast is still unknown. The continuity of a long term project like this is important in order to estimate population abundance and rates of population growth. B. There is a gap in the information about the SRW. Research in neighbouring countries (Argentina and Brazil) has been conducted for 35 years and 22 years, respectively. Because of the migration movements of SRW between the Argentinean and Brazilian reproductive sites, and the strategic location of Uruguay (between Argentina and Brazil),
we hypothesized the existence of a link between the two mentioned SRW reproductive sites in the South-western Atlantic. Furthermore, the role of the Uruguayan coast in the ecology and migratory patterns of the species need to addressed. C. Management and conservation. In 2002, to attract tourism in the winter season, the Uruguayan Government started an ecotourism program (vessel and shore based whalewatching). This program begun without any scientific basis about the impact of ecotourism on SRW. Biological information obtained from this project will be extremely important for the welfare and conservation of the species in Uruguay. The information collected in this project may be used to implement conservation and management plan in Marine Protected Areas, and for conservation activities in the south-western Atlantic.
Project DescriptionAims The data generated from this project will be used: a) To determine the status of the population of SRW; b) To identify potential Marine Protected Areas for SRW; c) To establish conservation and management plans for SRW in Uruguay.
Objectives 1. To determine the importance of the Uruguayan coast in the breeding range and migratory route for SRW 2. To study the long term population dynamics (spatial and temporal distribution) of SRW. 3. Create a high-quality of SRW photo-identification catalogue. 4. Compared the Uruguayan SRW photo-identification catalogue with the Brazils and Argentinas SRW photo-identification catalogue. 5. To study the migratory pattern, permanence time of individuals and the relationship between the Uruguayan population and the populations in the region. 6. To study the mating, social and mother-calf behaviour of SRW. 7. To increase local people awareness of the role of SRW in the marine ecosystem and the importance of Marine Protected Areas.
MATERIAL AND METHODS
Study area: Transect aerial surveys will be performed fortnightly (August to November) and along the coast (250 km) from Punta Ballena (Maldonado Department) to Santa Teresa (Rocha Department), Uruguay.