Winter Storms and Island Erosion

“You’ll smell it before you see it” I was told on board the Freda B while we sailed towards the South Farallon Islands. As we approached our soon to be home, the smell of the island drifted amongst us but all I could see was the thick wall of fog in front of me.  Suddenly, the rocks of Southeast Farallon Island (SEFI) were visible, jutting straight out of the water, like something from a movie, less than a mile in front of me.  

The first few days of winter season stayed sunny and warm while we became acquainted with SEFI. As the end of our first week neared, what was predicted to be the biggest winter storm California had seen in years began to approach the island. It started slow at first as the swells grew larger crashing against the rocks. But then the wind picked up and the rain started pouring down.   

As we walked out the front door the morning after the storm began, dressed head to toe in foul-weather gear, we were greeted by something that looked more like a lake than the normal concrete path.  The excessive rainfall the night before caused the front yard to flood up to the top of the front steps.

Although the swells were coming from the opposite side of the island, at East Landing the waves were crashing over and around the crane. 

Over the last thirty years the South Farallon Islands (SEFI and West End Island) have seen an overall decrease in the pup population of the elephant seals that breed here. Storms similar to the one we experienced at the beginning of the season are thought to be a major contributing factor in this decline. As storms hit the islands, access points cows use to haul out are partially or completely eliminated. Areas around the island that were formally major breeding sites no longer have any elephant seals due to the removal of nice gradual inclines and soft sandy beaches as storms have battered and washed away the sand.

Northern Elephant Seal pup production on the Farallones (total), SEFI and WEI from 1972-2014. The 41 year mean is 227 pups (SD=134). The mean over the last decade is 121 (SD = 43). In 2014 there were a total of 67 pups produced (58 on SEFI and 9 on WEI).

This problem was shoved directly in our faces when our ninth cow of the season became lodged on a rock unable to get up or down while attempting to haul out using Log Channel. Late one morning as we were surveying our Mirounga colony, we noticed there was a cow stuck on a rock struggling to lift herself up onto the beach.  She would turn from side to side and try to push with her flippers but this only resulted in one of her claws getting ripped off from the pressure against the rocks.

At the end of the day, I went back to see if she had been able to get up or down but to my disappointment she was in almost the exact same position as we’d seen her that morning. For over an hour I sat and watched her. She had become increasingly more tired and attempted to move herself less often with longer breaks in between efforts.  Her breathing became more and more labored and her attempted calls would come out as rasps. When a male charged and rammed her, I hoped this would be the push she needed to get down but she just turned her head away and he eventually gave up. Knowing that the tide would not come in until morning, I worried about how this cow would respond to the stress and how the pressure of being wedged would affect the pup.  The next morning, cow -09 was still in the same position she had been stuck in since the day before. Growing increasingly more frustrated with the situation we debated on if there was anything we could or should do to help her but this was nature and not something we felt should be interfered with, so we left her as she was.  Later that afternoon, after being stuck for well over 24 hours, she managed to get down on her own and was floating happily in the small tide pool near where she’d been stuck.

The area where she’d been lodged used to be covered in sand making it a smooth access point for cows but due to storms it is now only accessible to the seals when it is high tide. Winter storms are predicted to increase in frequency and intensity over the next few decades and combined with sea level rise the quality of habitat for elephant seals may be in jeopardy. Elephant seals rely on large sandy beaches safe from high tide lines and storm surges but more and more of the island and coast line habitat they depend on is being lost to the ocean. The island’s breeding sites have become degraded over time and has resulted in a steady decline of the SEFI elephant seal population.

During our winter season on SEFI, we will be looking at the colony of elephant seals that breed here. Though it was a slow start to the season with only nine cows arriving in December, the New Year seems to have brought an influx of new life. As of Jaunary 5^th we have 18 cows in the main breeding colony, four of which have pupped.  As more cows arrive and start to pup, this season should prove to be both exciting and very busy.

The next instillation of Los Farallones blog will detail how we use these winter storms to harvest rain water and we have a new team member and introduction to make! Check back in soon to read more about what we've been up to.