I had my first head to head encounter with the Caribbean Spiny Lobster (Panulirus argus) two years ago in Belize. We were surveying populations to compare abundance, size and sex ratios between protected no-take zones and free-for-all fishing and recreation zones on the reef. Lobsters blend into the rocky crevices and depressions of coral reefs exceptionally well, almost imperceptible to the untrained eye but for their thick spiny antennae which poke out to perceive slight changes in current and chemical cues from conspecifics (other spiny lobsters). The first few dives were frustrating, I was hopeless at spotting them whereas everyone else seemed to be on the ball. The eyes grow accustomed to the salty underwater haze and the smudged colours of sponges and coral encrusting rocks, until finally detecting lobsters becomes second nature. If you find one, there are likely a few more hiding in its shadow. Lobsters tend to aggregate, for safety is in numbers when a nurse shark is prowling. As daylight diminishes and shadows elongate, spiny lobsters emerge from their dens to forage for molluscs, small crustaceans and urchins. After their nocturnal feeding spree, olfactory cues lead them back to shelter.
My fascination for this species grew with every dive as I began to appreciate its highly social behaviour. As expected, lobsters were larger and more abundant in the protected zones of the reef, size-selective harvesting reducing the average size of lobsters in fished zones. Shocking numbers of lobsters were caught by fishermen every day and displayed on the jetties around the island of Caye Caulker, numbers that made me question sustainability of the fisheries. My dissertation being due next year, I chose an Operation Wallacea project dedicated to the Caribbean Spiny Lobster and submitted a draft research proposal entitled "The combined impacts of fishing and coral bleaching on populations of Caribbean Spiny Lobster in Tela Bay, Honduras". I have not yet received any feedback and the project will likely be postponed to 2021 due to the coronavirus pandemic but I thought I'd share my literature review of the topic and more importantly, my admiration for this particular lobster species.
Caribbean spiny lobster populations from the Florida Keys down to the Brazilian coast support crucial commercial as well as recreational fisheries. Many of the Caribbean’s formerly rich lobster grounds are now heavily overfished due to increasing demand on the global market and poor enforcement of existing regulations. The management of lobster fisheries in many countries relies on regulations of catch, such as minimum carapace length, spawning season closures and no-take of egg-bearing females. Rampant violation of minimum carapace size is a major issue in the Honduras fishery particularly, where an estimated 60% of lobster landings in weight are illegal-sized. These findings lead to the first aim of my project, which is to quantify and compare lobster populations in marine protected areas and fished areas of Tela Bay in Honduras (where the project is located). I am to use a standardised belt transect survey technique, which involves laying out two parallel 30 metres tapes to create a belt within which to record the number, size and sex of lobsters encountered. Statistically comparing the data collected in each zone will tell me whether there is a difference in population composition, the expected result being that a marine protected area hosts larger and more abundant populations of lobsters. A large enough dataset over many years can inform legislation and the creation of new protected areas.
One of the biggest problems with any attempt at conservation is data deficiency: where there is not enough data to prove the need for protection, no framework is in place to conserve and protect species or ecosystems. The IUCN Red List is used globally as a reference for conservation management and a quick scroll down the Caribbean spiny lobster page leaves no questions as to the reasons why this species is so devastatingly under protected. Categorised as data deficient and last updated in 2009, the abundance of lobsters is at least recognised to be decreasing and "it is likely that this species will be uplisted to a threat category" once more data on catch per unit is acquired.
Another subject of concern for spiny lobsters is the availability of suitable structurally complex coral habitat. The steady decline and loss of habitat to coral bleaching such as the 1998 and 2005 global events is thought to add pressure on lobster stocks by decreasing shelter and feeding opportunities. Reef-building corals provide critical three-dimensional structures and niches for lobsters to hide in, and are responsible for the high biodiversity and productivity of coral reef ecosystems. The human-induced loss of coral cover inevitably leads to loss of this structural complexity. Evidence for this has been found in the Caribbean sea and has been linked to reduced abundance of reef fish but there is a gap in the scientific literature when it comes to the effects of degradation of coral on Caribbean spiny lobsters. Qualifying coral structural complexity and linking it to lobster population composition is to be the second aim of my project, a bleaching event in October 2019 in Honduras providing the opportunity to assess the impact.
Now that the coronavirus has struck, the 2020 projects are likely to be cancelled and postponed to 2021, which robs me of the chance to collect my own data for a dissertation write-up. Operation Wallacea are providing us with data from previous years, which from what I have gathered focus on the shelter selection and feeding habits of lobsters rather than anthropogenic pressure. Nevertheless, research of any kind is much needed and I hope to contribute to the assembly of a large enough database to support conservation of the species internationally.
Below are a few facts about the Caribbean spiny lobster if I you aren't persuaded that they are COOL:
Lobsters grow in size by absorbing seawater between moults: once the hard external shell is shed, the soft body expands and grows a new exoskeleton.
The seasonal migrations of lobsters are spectacular, several hundred adults march across the sea floor into deeper waters in single-file lines, known as queues. The purpose of these migrations is not certain, they are likely to be in response to autumn storms.
Female lobsters release between 500,000 and 1.7 million eggs each time they spawn, amounting to 6-20 million eggs in a female's lifetime.
Lobsters have compound eyes, enabling them to detect orientation, form, light and colour.
It takes spiny lobsters upwards of 8 years to grow to the average size at which they are consumed.
Spiny lobsters live up to 20 years, which is 5 times shorter than the American lobster (100!), because metabolic processes are sped up and they age faster in warm Caribbean waters.
I hope you're convinced that these exceptional creatures deserve attention, protection and awe!
Sascha
