The Impact Of Climate Changes On Harbour Seals' Population

Climate change is a serious issue. Species all around the world are being affected by changes in their ecosystem that can be directly correlated to climate change. The duration of ice cover in the western Hudson Bay has decreased by three weeks in the last three decades (Florko, Bernhardt, Breiter, Ferguson, Hainstock, Young, Petersen, 2018). This decrease in sea ice may allow some animals to expand their range northward.

The animals that are affected by this phenomenon consist of Polar Bears, Ringed Seals, Bowhead Whales, and Beluga Whales, as well as the aforementioned Harbour Seal. Seals are very vulnerable to climate change because the rely on ice for resting, molting, and pupping. Pupping is the act in which the Seals come to land or shallow water in order to give birth. Today we’ll be focusing specifically on the Harbour Seal and how they are being affected by climate change and the changes in the ice condition in the western Hudson Bay.

Scientists in northern Manitoba set out to observe Harbour Seals at a known haul-out site. A haul-out site is a term used to describe the act in which a Seal comes out of water to spend time on land; this includes ice. Researchers set out to discover if reductions in sea ice were shifting the habitat in to one that is more favourable to Harbour Seals. Researchers chose a specific location in the Western Hudson Bay as their man vantage point of observation. We’ll be looking at these methods, results, and will have a discussion on the findings.

Seals were observed in the years, 1996, 1999, 2000, 2005, and from 2014-2016. Photos were taken using a specific type of photograph called a ‘Gigapan’. The researchers observed the Seals up until 2005 in two ways: systematically, which involved the researches using a pair of binoculars at various vantage points along the shore and from a boat situated in the central part of the river. The central location of the boat made it easier for researchers to observe the maximum amount of Seal activity.

The other method was approached opportunistically in which spots were chosen not necessarily on maximum seal observation. In later years, from 2014 to 2016, all observations were made from the same manmade location; a weir (a small dam) across the Churchill river at the upstream of the estuary. These sites were observed during these specific times, June to November 2014, June to September 2015, and May to October 2016. Seals were observed at the beginning of every hour from 6:00 - 22:00 and from 7:00 - 19:00 during the fall due to the shorter daylight period.

In the early years (1996, 1999, 2000, and 2005) researchers observed a modest amount of Harbour Seals in the western Hudson Bay. The highest observed in each year were 32 in 1996, 21 in 1999, 32 in 2000, and 15 in 2005. These are not totals observed over the course of a year, rather they are the highest number of Seals observed during a single day in the research period. The counts in the later years from the mad-made weir are astonishing. In the observational period of June - November 2014 the highest count observed on a single day was 110, from June - September 2015 the count was 80, and from June - October 2016 the highest count was 142. This data shows a significant increase in Harbour Seal activity over a two-decade period.

This data supports the hypothesis presented at the beginning of the report. Sea ice conditions are undoubtedly directly correlated with a change in Harbour Seal activity. The drastic increase over a relatively short time frame is an extreme cause for concern. Earlier access to the area may reduce the likelihood of Polar Bears preying on seals. Furthermore, another unprecedented discovery was made during the research period; Harbour Seals were observed pupping in the Churchill River area.

Pupping was not observed in the early research period, this suggests a drastic change in the Harbour Seal ecosystem in a short twenty-year period. The research team suggests that due to changes in observational techniques in the years 2014 - 2016, the data is skewed in a very conservative manner. The numbers from those years are a conservative estimate and in actuality the numbers are likely much higher. This is due to a limited vantage point in which researchers observed Harbour Seals in the later years.

The data from this study paints a clear, and disturbing picture. The researchers initial prediction of increased Harbour Seal activity in the area is confirmed. They go on to explain that the number of Harbour Seals in the area will continue to rise as changes in seasonal sea ice continue in the western Hudson Bay. The research team concludes by stating that population monitoring and further study of Harbour Seals in the Churchill River would provide more information to help assess the affects of climate in this ecosystem.