Habitat suitability and the effect of physical parameters on Finless Porpoise (Neophocaena phocaenoides) in the Khorkhoran wetland

Identification of the marine mammals’ suitable habitats is one of the requirements for coastal ecosystem conservation plans in southern Iran. A total of 42 points of Finless Porpoise (Neophocaena phocaenoides) presence were collected based on direct and random observation from late autumn to late winter of 2021. Depth map was created using a logarithm ratio model with a coefficient of determination of 0.784 and along with bed slope, channel width, average channel depth and width, channel length, channel width ratio and channel depth ratio (relative to the channels connected to it) were submitted into the Maxent model as predictor variables. The porpoise habitat suitability map was produced with an area under the curve of 0.887 for training and 0.832 for test data. According to the results of the Jackknife test, depth with an S-shaped response curve had the largest contribution (50.23%) to predicting suitable habitats of the porpoise. The suitability of the porpoise habitats increased with increasing depth and average channel depth, while the probability of the species' presence decreased with increasing slope, channel width, average channel width and channel length. The two variables of channel width ratio and channel depth ratio had insignificant effects on the probability of the species' presence. Moreover, an area of 4400 ha (10.6% of the total area) was identified as suitable habitat. Since these areas cover a small percentage of the study region and commercial fishing is performed more in such deep areas than the shallow waters, it is important to protect deep waters and reduce the resulting conflicts of interest with humans, thus ensuring the long-term survival of porpoise in the region. Therefore, it is necessary to outline porpoise conservation projects in deep areas and focus on efforts aiming to alleviate conflict with humans.