Posted by seahunt on December 17, 2002 at 14:53:44:
I'm not sure I want to revisit the otter issue, but I find it appropriate
for a couple of reasons. Also, this post should not get on anyones
nerves.
I have taken a particular point of view that is that either otters can hunt
or humans can hunt, but not both. Well, this is clearly prejudicial whether
valid or not. Being a scientist, I have to be honest and provide something of
the other point of view as well.
Now, this is clearly speculative, but that is valid, because speculation is
where scientific hypothesis' come from, including an unexpected and important
hypothesis such as one I found. Included in this speculation is a discussion
of the unknowns and weaknesses of the hypothesis as a tool for other honest
researchers to verify or discredit this hypothesis.
May I offer this view.
Say you take the opposing view that otters should re-establish themselves in
their ancient range. Now, this does rule out human hunting of their prey
species, but that is not the issue here. This is supposed to offer something
of a view of otters in an ecology undisturbed by humans.
OK, no hunting of otter prey by humans.
Well, the kelp, especially the smaller bottom species, gets thicker. As I
described, it gets so thick that the bottom is completely obscured. At the same
time, with no hunting of abalone, etc. by humans, certain micro-populations
that are out of reach of otters, but accessable to humans, thrive. These are
the ones in the deep cracks, many of which humans can harvest, but otters can't.
(Now this assumption is bit questionable, because you generally won't find urchin
populations of this description in the otter areas. They should be there, but I
didn't see them).
Anway, what this looks like is some mature members of the various prey species are
safe and so are out there merrily reproducing. Normally, they would never need to
go out of their safe spot for food. The optomistic view of this is that there is a
large recruitment of these prey species from those small protected populations. That,
combined with the extremely heavy bottom kelp to hide them, suggests that there
would be lots of little prey critters produced and that they might often get to a bit
larger size before consumption than what otters presently eat. This paints a slightly
better picture of the ecology for the otters than at present. There is a lot to
suggest that this is questionable, but it is about as optomistic as can be produced.
They might be a little less hungry.
Still, it does seem surprising that the otters exist in such a harsh situation.
Well, this brings up another speculation. One that is quite interesting I
think.
Project this a bit further. The discussion of otters is usually pretty much
confined to their present range above Point Conception. Notable of this area is
its vastness, lushness of the reef, relitively minor impact of humans and there
are no lobster to speak of. What is the picture of the otters in the lobster
areas? Well, considering that the otters seem only marginally adapted to the
food supply they currently have, could it be that the populations above the
lobster areas are in an area that they are not primarily adapted to. Are otters
as a specie, really primarily adapted to the lobster areas with more food and
milder conditions?
Considering that lobster are so resiliant to heavy human harvesting, is
that an adaptation to heavy natural otter predation? An undisturbed non-lobster
area can barely support local otter populations, even in an undisturbed state.
Does an undisturbed lobster area provide food to support otters at more than a near
starvation level? It well may.
Evidence to confirm or deny this question could be derived from a study of
the otter population distribution before otter hunting occured. Unfortunately,
I do not think this data exists, even the records of the otter harvest. If the
hunters found a much greater desity of otters in the lobster areas, it would
suggest that otters are really far more adapted to the lobster areas. It also
suggests that otters would very heavily impact the lobster fisheries.
Just some speculation.
Enjoy the diving, seahunt