Humpback whales and shipping collisions in the Dutch Caribbean EEZ

Student Report

This advisory report is drawn up at the behest of the Dutch Caribbean Nature Alliance (DCNA) who wants to know how to reduce ship strikes with Humpback whales. In the current situation around 30 whales a year die due to ship strikes, this has doubled compared to 5 years ago when this was 12-14 deaths a year. The aim of this report is to limit or prevent damage to humpback whales in the Caribbean, brought on by the shipping routes of cruise ships, cargo ships, private yachts, and fishing boats. To answer this, a qualitative study was conducted, for which a literature review was done. In addition to the research an expert was contacted to provide additional knowledge. This research has shown that there a three main factors to the severity of collisions. The first factor is that areas with high densities of whales overlap with areas where there are many ships. Secondly, vessels traveling at a higher speed poses a higher risk of fatal injury. At a speed of 12 knots the chance of whale mortality is 50%, at 14 knots it is 70% and at 18 knots the chance of whale mortality is 90%. Lastly, lactating female humpback whales spent 53% of their time within 3 meters of the surface. Near the surface animals are more at risk of collision because they are within reach of a vessels’ hull and propeller.

To reduce the risk of a ship strike, multiple solutions were devised.

1. Establishing vessel speed restrictions of maximum 10 kts in national waters

2. Educating and alerting vessel and watercraft operators to the dangers to whales of collisions

3. Developing and implementing Mandatory Ship Reporting Systems with the Coast Guard

4. Establishing temporary precautionary zones, called Dynamic Management Areas, around recently sighted humpback whale groups

5. Working with the Coast Guard to establish recommended vessel routes and approaches to ports.

6. Using an acoustic harassment device (AHDs) when spotting whales

A multi-criteria decision analysis was used to evaluate which solution or solutions are the best to recommend. Upon dissecting the analysis, it is recommended to use solution 3 with the regulations of solution 1 and 4. The solution we propose is an app for reporting whale sightings and advising captains. This app can be used by both commercial vessels and recreational users. It is also mandatory to have a maximum speed of 10 kts within the national waters off the Dutch EEZ islands. This can be mandated up to 12 miles offshore of the islands. To still ensure that vessels are mindful of whales during the migration season, the advice is to also establish a quality mark. This label is given to a vessel that is using the app outside of the national waters of the Dutch EEZ islands.