Report on 14 Large Whales That Died due to Ship Strikes off the Coast of Sri Lanka, 2010–2014

Abstract

The greatest threat to cetaceans in Sri Lankan waters was considered to be the direct take of small-and medium-sized cetaceans using harpoons and/or as bycatch until recently. However, ship strikes have probably been occurring for years but have not been recognized for what they were. For the current study, only animals with visible and prominent injuries related to collisions were evaluated. Data gathered between 2010 and 2014 included the species, morphometry, location, and date; tissue samples were collected for genetic analysis. When possible, a complete necropsy was conducted; otherwise, partial necropsies were conducted. The study confirmed 14 reports of ship strikes between whales and vessels out of all the strandings reported from 2010 to 2014. Most strikes ( = 09, 64%) involved blue whales (Balaenoptera musculus), although three other species were also documented, one Cuvier's beaked whale, two great sperm whales, and one Bryde's whale, as well as one unidentified baleen whale. Collision hotspots such as the southern waters of Sri Lanka are areas that warrant special attention in the form of vessel routing measures or speed limits, research on cetacean ecology, distribution, daily and seasonal movements, public service announcements, increased law enforcement presence, and other measures.

Skull and Neck Lesions in a Long-Finned Pilot Whale (Globicephala melas): A Result of Ship Collision?

“…Here, we have documented and described blunt trauma in a dead pilot whale. Fractured vertebrae can occur when whales collide with fast-moving, heavy ships [ 14 ]. In this case, we identified major internal head and neck lesions that were not visible from the outside.…”

“…The whales here are naturally at greatest risk at the surface. However, previous studies have shown that whales are more vulnerable to collision when they feed and socialize [ 14 ].…”

Cetacean occurrence and diversity in whale‐watching waters off Mirissa, Southern Sri Lanka

“…The continental slope region also coincides with one of the busiest shipping routes in the world (Priyadarshana et al 2016). Over 5000 ships pass through these waters every month (Nanayakkara & Herath 2017) (Fig. 1).…”

“…The general issue is that an extensive shipping lane crosses an area populated by cetaceans in the southern territorial sea, and oil, chemicals, toxic materials, and other goods are constantly transported by various large vessels (de Vos et al 2016). In the case of an accidental ship-to-whale collision, cetaceans and all marine organisms living in the area can be significantly affected (Randage et al 2014;Priyadarshana et al 2016;Nanayakkara & Herath 2017).…”

“…Due to these activities, southern Sri Lanka's cetaceans are extremely vulnerable to impacts from marine traffic. For example, fairly high annual mortalities have been recorded for spinner dolphins [Stenella longirostris (Gray, 1828)] and blue whales [Balaenoptera musculus (Linnaeus, 1758)] in this area in the past few years (Dayaratne & Joseph 1993;Ilangakoon et al 2000;Nanayakkara & Herath 2017). However, the contributions of unusual mortalities and increased public awareness resulting increase in sightings and reporting efforts cannot be distinguished when considering the increase in strandings (Foord et al 2019).…”