"I thought scampi was a prawn?!"
Scampi, despite commonly thought of as a prawn or a shrimp, is actually a species of clawed lobster. Mind blown? Other common names include langoustine, the Norway lobster, Nephrops, and the Dublin Bay prawn (the latter of which probably contributes to the prawn-shrimp-lobster confusion!). Scampi is a smaller cousin of the more well-known clawed lobsters, the European lobster and the American lobster.
Scientific name: Nephrops norvegicus
Life in the deep
Scampi live and take shelter in self-dug burrows just below the seafloor, which contrasts with their larger cousins who hide within rocky crevices on the seafloor. Scampi also live in deeper waters, up to 800 m deep! However, like their larger cousins, the dinner bells only ring at night when they scour the seafloor looking for a tasty meal (molluscs, worms and other crustaceans are usually on the menu).
A famed fishery
As a seafood commodity, Nephrops is worth a whopping 80 million pounds to the UK economy each year, with typically around 30,000 tonnes landed annually, mainly in Scotland (Seafish 2018). In terms of weight, that's equivalent to 5,000 male African elephants. Moreover, to put the economic benefits into context, Nephrops is the UK's most valuable shellfish species (in second place are scallops which are worth around 75 million pounds annually), and brings in more cash annually than cod, plaice, sole and whiting combined! So it is not too bold to say that the Norway lobster is one of the UK's most important fisheries.
Catching Nephrops is usually done by deploying creels or trawls. Unfortunately, the latter can sometimes have damaging environmental impacts on non-target marine life living on the seabed, such as seagrass beds and sedentary soft corals. Incidentally, Nephrops caught using creels have much higher survival rates than trawls and are usually sold live as 'langoustine' which are worth up to five times more than trawl-caught Nephrops in which only their tails are processed and sold as 'scampi'.
Adriatic Sea: the Pomo puzzle
Scampi are not only found around the UK and in the northeast Atlantic Ocean - they have also established populations in the Mediterranean. Although they are generally not as abundant in the Med, they do exist in some concentrated hotspots, such as in the Adriatic Sea. Like in the UK, scampi are commercially important for the Italian and Croatian economies and are therefore intensively targeted across parts of the Adriatic Sea. However, as Uncle Ben would say, with great power comes great responsibility, because like many other fisheries scampi are not immune to overfishing. In the Adriatic, the current management regulations separate the Nephrops fishery into two management units or geographical sub areas (GSAs), GSA 17 and GSA 18.
However, recent data collected from fisheries scientists have revealed notable differences in growth rates between scampi populations in the "Pomo Pit" region of GSA 17 compared to populations outside of the Pit. It appears as though scampi, and particularly female scampi, living in these 150-250 metre-deep pits grow at a slower pace and are generally smaller than their outside counterparts.
But what is causing this size dimorphism? Differences in depth? Or could it be a response to fishing, whereby individuals divert investment from growth into maturation so they have more chance of producing offspring before they are caught. There is some evidence for this happening in fish. Or perhaps populations in Pomo Pit have always been smaller and slower growing. One way we could try to answer this question is by exploring the genetic profiles of scampi inside and outside of Pomo Pit. If we find that populations inside and outside are virtually the same genetically then it could point towards fishers preferentially removing larger individuals from the Pomo Pit populations. On the other hand, if scampi in the pits are genetically different from their outside counterparts this might suggest that Pomo Pit populations are isolated from the rest of the Adriatic Sea, and that they have been on a different evolutionary path for some time.
This type of genetic study is precisely what our team are currently doing! We have collected tissue samples from a number of scampi at different sites (yellow dots on the map above) and we are going to test how genetically similar or different they are from each other by analysing variations in their DNA. After the analysis, we will hopefully be in a position to answer this interesting size dimorphism dilemma!
Final food for thought
If genetic analysis reveals isolation of Pomo Pit scampi then this could mean that we need to change the way we manage fishing activity in these pits. This is because the fishing regulations that are in place for GSA 17, including size and catch limits, might not be appropriate for scampi in Pomo Pit. And if the correct measures are not enforced, there may be population declines in the pits which would affect the productivity and profitability of the fishery.
For future updates about the project please follow my Twitter or ResearchGate project page!