OPEN JOURNAL OF OCEAN AND COASTAL SCIENCES Volume 1, Number 1, October 2014 OPEN JOURNAL OF OCEAN AND COASTAL SCIENCES Nesting Ridleys Need Critical Protection and Its High Nest Successes at Devi Coast Odisha Behera S. K. 1*, Kar C. S.2, K. Sivakumar3 and Choudhury B. C.3 1 Integrated Coastal Zone Management Unit Berhampur, Odisha, India. 2 Department of Forest and Environment, Bhubaneswar, Odisha, India. 3 Wildlife Institute of India, Chandrabani, #18 Dehradun, Uttrakhanda, India. *Corresponding author: [email protected] Abstract: Olive Ridleys sea turtle are known to nests both enmass and solitary in the south sand spit of River Devi, Odisha. After 1999 enmass nesting, only solitary activity is observed in this part of beach. This study was done to evaluate the nesting activity along Devi coast for period of four years, 2006-10 and hatchling successes of Olive Ridley solitary nests in one of the island where no human habitation is present was carried out from December 2008 to May 2010, in total 7642 numbers of nests was recorded within four years of which 5058 nest were from the main land beach and rest 2584 from island beach. A total of 309, nests were marked with a pole and monitored for hatchling successes. It was calculated, 94% of eggs were hatched successfully, and 91% of hatchling emerged out successfully. This study shows that nest located between 20 to 40 m distances from the high tide mark were more successful than the nest in other part of the beach. There was not much difference in the hatchling successes between the three periods of nesting (nesting, peak nesting, post nesting) and within years. Since high level nesting activity and high hatchling successes of nests were observed, Devi rookery still to be a potential mass nesting ground provided near off-shore fishing is managed properly especially during peak breeding period between February and April. Intensive near off-shore fishing are assumed to be reason for non-occurrence of mass nesting in the Devi rookery. Higher number of stranded turtles coincides with the peak nesting time during the study period. Keywords: Olive Ridley; Nest Density; Devi; Hatchling Successes; Mortality 1. INTRODUCTION The olive ridley turtle (Lepidochelys olivacea) generally opt to lay the eggs on beaches with high humidity levels. Most of these are found near large and small river mouths or estuaries [1, 2]. Similarly, solitary nesting activity is found all along the coast of Odisha during the nesting season i.e. December to May. This study confirms that the nesting activity is throughout year like Gahirmatha [3] and only few instances mass nesting has being recorded yet after the discovery of this nesting beach in (1981 Kar) when mass nesting took place, but there is no record of estimation. After a gap of five year another mass 25 OPEN JOURNAL OF OCEAN AND COASTAL SCIENCES nesting took place in 1984-85. During the year 1996-97 [4] 3rd mass nesting took place and the last mass nesting was recorded during 1998-99 [4] after that there is no record of mass nesting till date. Apart from this solitary nesting activity occurs throughout the year. Solitary nesting activity reaches its peak between February to April; the nesting phenomenon gradually decreases in coming months. Although most nest are predated or destroyed by jackals, stray dogs in the main land beach but nests in one of the island, from where the mass nesting have being reported is total predator free and almost all the nest are naturally hatched and hatching goes to sea after hatching. Solitary nesting, mortality is higher during the breeding period in comparisons to any other beaches along the Odisha coast [? ]. Mortality of the turtles is due to intense fishing activity in near shore water during the breeding season [? ]. Most of the mortality results due to high near shore fishing in this region during the nesting and peak nesting period, January to February [? ] and in subsequent months. This was an attempt to study the pattern of mortality and nesting which is induced by intense near shore fishing activity at Devi rookery. There are many studies on the hatchling successes of two rookeries along the east coast of Odisha, these studies are restricted to the mass nesting beaches and done during the mass nesting period [3–7]. No such studies had yet been done on the hatchling successes rate of the solitary nesting activity along the east coast of Odisha. This study will put light on the hatchling successes rate of turtles at Devi rookery and the activity of fishing affecting the nesting of turtles. 2. STUDY AREA This nesting beach is located between the border of Jagatsinghpur and Puri District of Odisha. Devi coast is stretched on the either side of river Devi (N 19◦ 57’ 36.0” E 86◦ 23’ 05.5”), towards north it is stretched up to Petaphutai river mouth (N 20◦ 37’0.60” E 86◦ 25’59.41”) and up to Kadua river mouth towards south (N 19◦ 54’ 31.4” E 86◦ 14’ 24.0”) total stretch is 32 km. the total stretch is planted with casurina forest near to the shore line. Toward northeast of Devi mouth a island is present which is devoid of vegetation It has a sandy beach of about 1.5 km in length; the beach is approximately 150 m Wide from the high tide line to the other side of the island and has a soft slope. In this remote Island we observed nesting of Lepidochelys olivacea from December 2006 to May 2010. 3. Result and Discussion 3.1 Main land (Kadua Mouth to Devi Mouth) During the study period (2006 to 2010) there was no arribada nesting. However, the high solitary nesting was observed at Devi rookeries during the study period (Figure1 ) where more than 100 turtles nested in single night on this beach. During 2010 more than 500 turtles nested in a single night and this event lasted for two days in the island of Devi rookery. This event is an indication towards the potentiality of the enmass nesting. But the exact reason why mass nesting fails during certain year is not known but they may be influenced by the surrounding environment including anthropogenic disturbances and changes in beach geomorphology of the nesting area. Beach monitoring was done from throughout year, for encountering nesting activities. The main nesting activity starts from December every year and reaches its peak during the month of February and March every year. The highest nests were recorded within February to March during 2006-07 (240), 2008-09 (682) and 2009-10 (739). Late nesting was observed during 2007-08 which take place during the month 26 Nesting Ridleys Need Critical Protection and Its High Nest Successes at Devi Coast Odisha Map showing the mass nesting island (Robert Island) and the main land from Devi to Kadua mouth. Table 1. Nest and nest density per day of olive ridley turtles in main land (kadua to Devi river mouth) monthly basis during 2006 to 2010 at Devi rookery. Year 2006-07 2007-08 2008-09 2009-10 N Nd N Nd N Nd N Nd June - - - - 2 2 1 1 July - - 1 1 1 1 - - August - - 1 1 - 1 1 September - - - 2 2 2 2 October - - 1 1 2 2 5 1.6 November - - 1 1 1 1 1 1 December - - 1 1 4 2.00 41 4.56 January 21 1.91 5 1.67 53 5.89 92 8.36 February 44 2.93 94 3.92 682 40.12 739 49.27 March 240 10.91 354 15.39 628 25.12 677 32.24 April 209 11.00 481 22.90 275 13.10 328 25.23 May - - - - 27 4.50 41 3.73 N= Number of nest; Nd= Nest density/day of April. One way ANOVA was carried out on the nesting density of the turtles between the years for each years, showed significant variation between the seasons (F = 1.109, df = 3 P < 0.36). We conclude that there was statistically significant difference in the mean of turtle nesting density within the years in all four years of study period. During the four years (2006-07; 2007-08; 2008-09 & 2009-10) of study period we observed 67, 76, 89, 88 days where there was nesting crawls and in remaining nights there were no nesting or false nesting crawls by turtles respectively. The highest nesting activities were recorded during March (22, 23, 25, 21 days out of 31 days for each respective year). However, in terms of nesting aggregation, maximum numbers of turtles were encountered on the beach during April 2006-07 and 2007-08 whereas in 2008-09 and 2009-10 it was highest in February (Table1 ). Maximum numbers of nests were recorded between 20-30 m from HTL and 70- 80 m from the vegetation line (Figure2 & Figure3 ). 27 OPEN JOURNAL OF OCEAN AND COASTAL SCIENCES Figure 1. Nesting recorded during 2006 to 2010 nesting season (December – May) at Devi rookery. Figure 2. Distance of olive ridley nests from the high tide line at Devi rookery during 2006-10. Figure 3. Distance of olive ridley nests from the vegetation line at Devi rookery during 2006-10. 28 Nesting Ridleys Need Critical Protection and Its High Nest Successes at Devi Coast Odisha Table 2. Nesting at new Akashdhia Island of Devi rookery. Year 2006-07 2007-08 2008-09 2009-10 Month N Nd N Nd N Nd N Nd October - - - - 2 2 3 1.5 November - - - - 5 1.6 7 1.75 December - - - - 37 6.16 42 10.5 January - - - - 39 13.00 41 13.66 February 21 3.00 16 4.00 57 14.24 138 23.00 March 35 5.83 49 9.8 49 7 1811 164.63 April 58 14.5 53 17.66 53 8.83 29 7.25 May - - - - 23 3.83 16 2.66 N= Number of nest; Nd= Nest density/day 3.2 Solitary Nesting at Island (Akashdhia) Beach monitoring was done from October to May during all four years for encountering nesting activities.