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High Hatching Success of Saltwater Crocodile (crocodylus Porosus) in a Commercial Crocodile Farm of Bangladesh

Md. Sakhawat Hossain
Department of Zoology, University of Dhaka, Dhaka-1000.

M. Firoj Jaman
Department of Zoology, University of Dhaka, Dhaka-1000.

Mushtaq Ahmed
Department of Zoology, University of Dhaka, Dhaka-1000.

Md. Mokhlesur Rahman
Department of Zoology, University of Dhaka, Dhaka-1000.

Md. Saidur Rahman
Department of Zoology, University of Dhaka, Dhaka-1000.

Abstract/ Executive Summary:

An extensive study was conducted from March 2007 to February 2012 on hatching success of saltwater crocodile (Crocodylus porosus) in the Reptiles Farm Ltd. (RFL) located at Hatiber village of Uthura union under Bhaluka upazila in Mymensingh. The study was mainly based on direct field observation and some previous data collected by farm’s technicians. A special type of incubator having 98-100% moisture and 31-33⁰C temperature was maintained to improve the hatching success. Yearly hatching success in captivity was 95.8%, 95.15%, 97.44%, 96.03% and 94.53% in 2007 through 2011, respectively. The average rate of hatching success in RFL was 95.8 ± 1.09%. Hundred percent hatching success was found in 29 out of 56 clutches. Clutch size varied from 19 to 68 eggs. Unhatched eggs were 4.19%, of which most of the embryos died before hatching. The average time required for incubation was 79 ± 3, 79.5 ± 4.5, 80 ± 4, 80.5 ± 4.5 and 78.5 ± 3.5 days in the above mentioned period. Compared to the wild habitat, captive environment in controlled weather and predation might improve hatching rates. This study suggests that conservation of this endangered species is possible by captive breeding and reintroduction program.

Keywords: Clutch size, Incubation, Hatching, Captive breeding, Saltwater crocodile.

Location: Hatiber village of Uthura union under Bhaluka upazila in Mymensingh

Start Date: 00-03-2007

End Date: 00-02-2012

Program Area: Animal Health and Management

Commodity: Crocodile

Objectives:

Current study was conducted on the breeding activities of saltwater crocodile (Crocodylus porosus) in a commercial crocodile farm to reveal the factors affecting hatching rates in captivity.

Methodology:

Study Area: Reptiles Farm Ltd. (RFL) situated in Hatiber village of Uthura union under Bhaluka upazila in Mymensingh. It is spread over 13.4 acres of land and located on 24°26′52.38″ Northern altitude and 90°15′50.94″ Eastern longitude. Study was conducted between March 2007 and February 2012 in the Reptiles Farm Ltd (RFL). The observation was started early in the morning and was continued still afternoon. The study was mainly based on direct field observation and some previous data collected by the farm technicians for their computer record. Weather data has been collected from the weather recording devices located at the farm.
We observed female breeders along with the technicians during egg laying time when and whether the breeders laying eggs in the ponds. Eggs were collected within 24 hours or immediately after egg laying. Female crocodile shad showed less aggressiveness for exhaustion. Angle of collected eggs from the mound nest was maintained and numbered with pencil markers. Collected eggs were cleaned up and placed on plastic tray on moisture soil and maintained the collected orientation of the eggs in the nest. One tray was for one clutch and a collected time of the clutch was recorded. Once eggs were collected, the top orientation of the egg in the nest was marked and placed in the incubator in approximately the same position to prevent embryo mortality (Hutton & Webb, 1994; Ojeda et al., 1998). A special type of incubator is on the farming area, where 98-100% moistures and 31-33⁰C temperature was maintained for the better success of hatching. We used incubation trays because it allowed easy access to the eggs in order to remove infertile eggs and may reduce the danger of rotting and contamination. Easy air access to the incubator room also prevents overheating from the metabolic heat produced by the embryo with the banding pattern on the eggs. Eggs which were showed banding pattern kept as fertile and which were not selected as infertile. The temperature and humidity data was collected from the thermometer and hygrometer attached within the incubator. Door of the incubator was opened for 30 minutes at the morning and 30 minutes at the evening in order to maintain oxygen level. In constant temperature, 75-85 days were required for hatching in the incubator. Banded and damaged eggs were recorded on regular basis. Non-banding eggs were sorted out within 48 hours after placing in the incubator.

Source of Information: Univ. j. zool. Rajshahi Univ. Vol. 31, 2012 pp. 35-38 ISSN 1023-6104

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Keeping and breeding of crocodile in the captivity is an effective protective measure. Breeding also makes possible to commercially exploit crocodiles legally within the framework of CITES. We found that control of air temperature and air humidity can improves hatching rates. We also observed that protection from predators and providing provisioning food may increase survival rate of young crocodiles.

Knowledge Management: Journal