1 week Ago By Ruth Schuster
The blackchin guitarfish lives around the coasts of the balmy Mediterranean Sea and in shallow Atlantic waters from Angola to Portugal. You probably won't encounter it, though, because it has become critically endangered, according to the International Union for Conservation of Nature. This not-small cousin of sharks and rays, looking sort of like both with a flattened ray-like head and shark-like body, is not dangerous to humans.
It has a beige-colored back and is about 1.5 meters (4.9 feet) long in adulthood.
It is most prevalent off the shores of West Africa . Yet now scientists at the University of Haifa claim to have identified a nursery of the odd-looking animals along the Mediterranean coast near Ma'agan Michael. Their discovery was published in Frontiers in Marine Science in June.
Once common in the Mediterranean Sea, the fish's numbers have contracted by at least 80 percent in the last 45 years, experts estimate. Its chief problems are us, us and us, and also being a large animal that reproduces slowly and has few offspring. Blackchin guitarfish like shallow warm waters and, being delicious, are vulnerable to our predation – not to mention their habitat is becoming ever fouler.
How climate change and the rise in sea temperatures will affect them remains unknown. In any case, discovery of a nursery for this beleaguered species is good news on the grounds that its identification could spur Israel to declare the area a nature reserve, explains University of Haifa spokesman Itai Shainer. We note that the Mediterranean Sea has two species of guitarfish: the common guitarfish ( Rhinobatos rhinobatos ) and the blackchin guitarfish ( Glaucostegus cemiculus ).
This story is about the latter. What is a fish nursery? It isn't necessarily where the fish mate but a natural area where the younglings can find food and are relatively protected from predators and extreme weather conditions, says doctoral student Eynav Cohen, a co-author on the paper. The nursery was identified following 40 years of fishermen observing baby blackchin guitarfish around Ma'agan Michael between June to November.
Now, not every place thronged with fishlings is a nursery. Based on the citizen science observations by fish hunters, the team set out to verify the observations and elucidate whether Ma'agan Michael fulfills the criteria for a blackchin guitarfish nursery. It is, they concluded, based on the three criteria for declaring a fish nursery created by one Michelle Heupel, who has specialized in research on nursery grounds of cartilaginous fish.
One: They spotted much more baby guitarfish in the right-kilometer stretch that comprises Ma'agan Michael beach, compared to Caesarea right up the coast, which has much the same topological features. Two: The team actually caught and tagged a bunch of the juvenile fish between August to September each year from 2017 to 2019. The kiddies were 25 to 35 centimeters in length, bless them.
How these fish were handled and tagged when netted is explained at loving length in the paper. Anyway, they were released unharmed, if presumably peeved. "All guitarfish caught and handled were returned to the sea without injury within 10 minutes of capture, with no mortality recorded because of the operation," the team reassures.
The young ones stayed in the embrace of Ma'agan Michael for extended periods, growing and becoming better able to survive in the open waters – which was the point that needed proving. Three: Monitoring showed that from year to year, juvenile blackchin guitarfish were spotted at Ma'agan Michael – this was not a one-off. Though it could become rarer because the unhappy fish is in critical danger of extinction.
In off-season (meaning not from September to November), there were hardly any blackchin guitarfish to be found at Ma'agan Michael – but then we did point out how rare they have become. What might the attraction of Ma'agan Michael be? It features lovely sandy beaches, but from the piscine perspective the southern point of the stretch is bordered by the Taninim River estuary. That enters the Mediterranean Sea at the coastal village of Jisr al-Zarqa and carries sediment and organic matter into the sea, enriching the waters.
Moreover, the kurkar sandstone cliffs characterizing much of the coast create a wealth of places for young fish to hide. As for the choice of Caesarea as a point for comparison, they needed a place with similar physical characteristics, the team explained. So what have we? The team is confident it has identified a natural nursery for a cousin of the shark in extreme danger of extinction.
This cousin, the blackchin guitarfish, is fished and eaten when the opportunity beckons. It would therefore be good for the sake of the fish and planet to declare this stretch to be a marine nature reserve, or in any case out of bounds for any fishing. Apropos of which, the Mediterranean Sea is considered to be one of the most overfished major water bodies in the world.
Overfishing is a worldwide problem, but research has shown that in the Mediterranean Sea it is driven by large-scale fisheries, not grizzled nicotine addicts with a boat and a net. Overfishing refers to catching them beyond the point of population sustainability. The blackchin guitarfish is exactly the sort to be worst affected by our fishing practices, given its tastiness, habitat and slow reproduction.
The study was commenced by student Barak Azrieli from the Sharks in Israel nonprofit during their master's degree, supervised by Aviad Scheinin and Prof. Dan Tchernov at the research station..
