Monday 19 February 2024

Investigating Crocodile attacks around Roviana Lagoon, New Georgia, the Solomon Islands.

Saltwater Crocodiles, Crocodylus porosus, are found in coastal environments in the Asia-Pacific region from the Bay of Bengal, throughout Southeast Asia and New Guinea, to northern Australia, and as far east as the Solomon Islands. Unlike other Crocodile species, they are not currently considered to be threatened, being classified as of Least Concern under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. However, this assessment is essentially dependent on good relations between Human and Crocodile populations; Saltwater Crocodiles will attack Humans and livestock, causing injuries and deaths, as well as less obvious economic damage by excluding Humans from areas where they become dangerous. This in turn can lead to retaliatory actions by Humans, removing troublesome Crocodiles, or sometimes whole populations, from areas where they are seen as harmful. 

Saltwater Crocodiles feed in tidal rivers and creeks, freshwater lakes and Mangrove forests, and will occasionally forage on Coral reefs. While they cross open sea to seek new territory, they do not usually hunt or feed there. Female Saltwater Crocodiles can reach about 3 m in length, and can weigh as much as 150 kg, but the largest males can reach more than 6 m in length and weigh more than 1000 kg. Males will try to defend a territory and the females within it, chasing away smaller males, who then go on to look for territories of their own, which can lead to changes in the social structure and behaviour of Crocodile groups.

In a paper published in the journal Orynx on 22 January 2024, Shankar Aswani of Rhodes University and Joshua Matazima of the University of Queensland present the results of a study of negative Human-Crocodile interactions around Roviana Lagoon on the island of New Georgia in the Solomon Islands.

A previous study examined Human-Crocodile interactions across the Solomon Islands over the period 1998-2017. This study identified 225 Crocodile attacks across the islands, with 83 of these being fatal, including 31 on children. Aswani and Matazima's study concentrates on a much smaller area, and is aimed at understanding Human-Crocodile interactions in a specific, localised environment with a view to developing specific policies for that location, something which it is difficult to achieve from wider scale national surveys.

Aswani and Matazima's study concentrated on four villages, Dunde, Baraulu, Nusa Hope, and Kozou, located on the 700 km² Roviana Lagoon, on the southwest of New Georgia island. Each village has a population of between 50 and 300 people. Twenty three men and thirty seven women from sixty households across the four villages were interviewed by three locally hired assistants, in the local Roviana language. Twenty of the interviewees reported that a member of their household being attacked by a Crocodile between 2000 and 2020, four in Dunde, seven in Baraulu, five in Nusa Hope and four in Kozou.

Locations of the four villages (Dunde, Baraulu, Nusa Hope and Kozou) in which residents were interviewed regarding incidents with Saltwater Srocodiles, Crocodylus porosus, in  Roviana Lagoon, New Georgia Group, western Solomon Islands, during 2000-2020. Aswani & Matazima (2024).

A total of twenty attacks were recalled, of which two were fatal. Ten of the recalled incidents happened in the evening, eight in the afternoon, and two in the morning. Sixteen victims were female, and four were male; one woman and one man were killed during the study period. Two were under twenty years of age, eight were between 20 and 39, two were 40-59, and eight were over sixty years of age. The majority of the victims were attacked while collecting shellfish along the sea shore and in Mangrove forests. Ten of the victims were attacked when the water was murky, with the other ten attacked when the water was clear. No retaliatory attacks were made against Crocodiles be the people of the area.

The pattern of attacks recorded in Roviana Lagoon were quite different to that recorded in the Solomon Islands-wide survey, although it may be similar to other localised areas within the nation. Across the Solomons, the majority of the victims were male, attacked at night while fishing, while in Roviana Lagoon the majority of the victims were female, attacked in the afternoon or early evening while gathering shellfish. Clearly, any system developed to minimize the number of Crocodile attacks based upon the national statistics would have little impact at Roviana Lagoon, since such a plan would likely concentrate on protecting men involved in night-fishing, an activity not practiced in Roviana Lagoon. Even a female specific plan developed from national statistics would be unlikely to be helpful, as across the Solomon Islands the majority of women are attacked while washing clothes.

Shellfish gathering, both for sustenance and sale, is an important activity to the women of Roviana Lagoon, but clearly leaves them vulnerable to attacks by Crocodiles. This activity is carried out almost exclusively by women, although they are frequently accompanied by children of both sexes. Most of the attacks happened in late afternoon or early evening, and water clarity did not appear to be a factor, possibly because the low sun shining onto clear water can make submerged Crocodiles just as hard to spot as the water being cloudy. 

Aswani and Matazima recommend that in order to minimise the number of Crocodile attacks, the women of Roviana Lagoon avoid collecting shellfish in the late afternoon and evening as much as possible, and that where this cannot be avoided, always forage in groups at this time of day, which will both improve the chances of spotting Crocodiles before attacks occur, and of rescuing any victims should attacks occur. They further recommend that future studies of Crocodile attacks focus on much narrower geographic areas when the purpose is to develop strategies to minimise attacks.

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