Seals of the River Blackwater…
Now we are entering into the warmer weather we have seen a lot more action out on the water. Throughout May we were lucky enough to enjoy 2 bank holiday weekends and we have been even more lucky to receive some beautiful, hot, sunshine, drawing many visitors and locals to the coastline.
The increase in the number of visitors reaching the coastlines has also seen the number of vessels on the water increase too. This month we are going to explore how the presence of jet skis, motorboats, speedboats, yachts, kayakers and other vessels have an impact on our local seal colony (if any)?!
To date over 150 hours have been spent observing the seals of the River Blackwater. We have become used to their: behaviours, swim, dive and feeding patterns. We also know the areas in which they like to play and the channel areas they like to use when moving from one location to another.
Our seals, like most others, enjoy hauling out on the mudflats between tides and sleeping under the sun’s rays. If left undisturbed, they will stay hauled out until the tide returns, signalling that it is time to feed. Usually one or two members of the colony can be seen scanning during this time on behalf of the entire colony.
So what happens when a vessel approaches or passes by this colony? Well, it depends on their size, whether they have an engine and their speed. Let’s start with vessels that are without an engine: paddle boards (SUP) and kayaks. These types of vessels can usually approach approx 200metres away from the colony, before we see a change in the group and individual behaviour.
We will see not just one or two members scanning intermittently, but two or three more will join in. Sometimes the odd one of two smaller seals of the colony will take to the shallows of the water and hey will reappear surrounding the vessels at a distance of 1-200m. If the SUP and kayaks are simply passing and moving slowly, the colony remains unthreatened and they will continue to rest and sleep.
Yachts under sail simply passing through the channel, generally does not receive any disturbance from the colony at all. Even when anchor is dropped approximately 3-400m away the colony remain in their usual behaviours. When we hear the arrival of a motor boat or speed boat the colonies behaviour changes entirely.
A speed boat travelling at speed will increase scanning behaviour by 100% from a distance of 7-800m. If the vessel continues on course for the colony, then the entire colony will evasively enter the water within 400m of the boat approaching; there is no messing around here, they are in the water within a flash and are later to be seen scattered, further up the river.
The seals will not return to their haul out site on the same tide during this encounter. When a vessel travelling under engine approaches the area of the seal colony at a slow speed, the scanning time of the individuals does increase by one or two individuals, but generally the colony will not enter the water unless the vessel stops within 200m of the colony.
Jet skis have a similar response to speed boats, however if the jet skis maintain their distance there is very little to no disturbance at all. The seals appear to be vigilant but happy to remain hauled out on the mud flats. When the Jet skis remain within the creeks and outside of the channels there is very little evasive behaviour displayed. This is a good indicator showing how water vessels and our local marine mammals can both enjoy and share the River Blackwater together, without creating disturbances.
The ZSL – Zoological Society of London – www.zsl.org has recently released a safe operating guide for vessels when coming in to contact with marine mammals. It has been quite clear from our observations that if the guidelines are followed and the community respects the water and the habitat in which the seals live, then the interactions between community and the environment can coexist side by side during the busy summer season.
Over the next few months will continue to monitor this behaviour and see if we can uncover if there is any other reason for them to chase each other about, rather than simply just playing with each other.
If you would like to be involved, receive our code of conduct of how to be responsible around seals or gain more information please see our contact details below:
If you see a marine mammal that appears to be in distress, hurt or injured please contact the BDMLR (British Divers Marine Life Rescue) or your local marine mammal medic Jacqui Monk on 07305 811349 – Keep a look out for our next article on the results of our Spring Survey of our Seals of the River Blackwater.
Jacqui Monk – MERI Marine School