Lionfish are not the only invasive
species in Cayman waters these days – scientists have found blue crayfish in
local ponds for the first time.
Crayfish are not native to the
Caribbean, but over the last 18 months, biologists have been finding blue
crayfish, also known as electric blue crayfish, in ponds in the Queen Elizabeth
II Botanic Park.
A visiting scientist, David Bass,
said it was too early to say how the crayfish, native to South Florida, would
affect the environment locally because they had been introduced so recently.
“Crayfish are not found anywhere in
the Caribbean. In fact, this particular species we came across, the Procambarus
Alleni, is located in South Florida. It’s the only other place it’s found, and
now in Grand Cayman,” said Mr. Bass, professor of biology at the University of
While he admitted he could not say
at this stage if the crayfish would have a detrimental impact on the plants and
creatures in the ponds where it is present, he said there were concerns worth
“The concern we have is that a
closely related species – same genus, different species – is a voracious
predator that has a severe impact on the food chain in several other areas of
the world. This is not the same guy, we are hoping it won’t have the same
impact, but we don’t know because it has never gotten out of South Florida
before – we don’t know what it will do when it leaves South Florida,” he said.
Staff at the Botanic Park discovered
the blue crayfish 18 months ago and contacted Mr. Bass, who has been visiting
Cayman for several years as part of an on-going study of local invertebrates in
the Islands’ freshwater systems. At first, he thought there may have been a
misunderstanding in the terminology and that what had been found was a shrimp
rather than a crayfish, because throughout the Caribbean some shrimp are
referred to as crayfish.
“But it was a crayfish, and I
thought ‘this is not good’. There are no crayfish in the Caribbean. I’ve been
collecting samples for years and I’ve never found one,” Mr. Bass said.
How the crayfish came to be in
Cayman is not known, although it is likely to have been introduced accidentally
when it was shipped here in the roots of an imported aquatic plant. “These
creatures are easily overlooked,” he said.
When Professor Bass was in Cayman
last month for his annual two-week visit, he returned to the pond where the
first crayfish was found, and discovered that not only were there more crayfish
at that site, there were others in ponds throughout the Botanic Park.
Although the Botanic Park is the
only place where the blue crayfish has been found, the fact that the crayfish
have spread within a year throughout the 65-acre garden and woodland preserve
is worrying to him and local scientists.
“It appears they have spread
throughout the Botanic Park. Last year, the wet season was reasonably dry. Now
we’re at the end of the dry season… When I come back again next year, the
ponds will have been flooded and the crayfish will have moved around,” Mr. Bass
He has been keeping the Cayman
Islands Department of Environment updated on his work.
“DoE is supporting the work and
will of course take any recommendations from Dr. Bass seriously and weigh them
against other priorities we are facing,” said Tim Austin, deputy director of
the Department of Environment.
“At this stage I don’t think we
will be undertaking any large scale monitoring work but will rely on
collaboration with Dr. Bass to chart a way forward depending on the magnitude
of the threat,” he added.
During his work on-island, Mr. Bass
also regularly takes samples and checks Governor’s Pond in Spotts Newland, but
said he had not found any evidence of the crayfish having spread to there.
Cayman is facing a wet and stormy
season with hurricane forecasters predicting that this year’s hurricane season
will be one of the most active on record in the Caribbean.
This may lead to the crayfish
spreading much further throughout the island, Mr. Bass said.
In early 2008, divers started
spotting lionfish in Little Cayman. That species, native to the Indian and
Pacific Oceans, has since spread throughout Cayman waters and is now a common
sight, causing major concerns about their impact on local reefs which contain
no natural predators to the fish.
Lionfish can produce 30,000 eggs a
month. They have huge appetites and can decimate the fish population of coral
reefs in weeks.