White sharks are declining, what are the consequences of their prey?

I study Losing a top predator in a wild area induces physiological and behavioral changes in the prey The decline in the number of top predators reflects the consequences that may occur on the prey and therefore on the balance of nature. Consider the model that White shark And Cape fur seal In Falls Bay, South Africa. Professor comments about the results Maria Berica Rasotto of the Department of Biology at the University of Padua.

“This is a particularly interesting model, because it has been studied since the turn of the century, so there has been more than twenty years of observation. Returns to the water and returns to give birth between November and December. The presence of white sharks indicates that these marine lions never leave the coast and fish in shallow water: they do not seem to move more than six meters off the coast. Animals that can go to very high depths. Moreover, over the years, their blood pressure levels have been studied by analyzing glucocorticoids in the blood. : In fact, we are talking about flying sharks ক্ষেত্রে in both cases, so, special behavior, together in that place, that is, this island, they propose and see themselves as a perfect model. Whether the difference in the number of predators can affect the behavior of the prey. “

Edit: Alyssa Spernelo

Twenty years of data, thousands of observations and a basic point: “Since 2015, the number of white sharks in that water has dropped dramatically. Since 2018, researchers have no longer been able to record hunting cases. For some years, these sea lions are no longer subject to predatory pressure. And what appeared? Glucocorticoid levels in marine lions have dropped dramatically: they are now pushing for coastal and deeper hunting. The absence of predators changes their behavior. Decreased stress levels affect reproduction: these animals reproduce much more now. “

Also in other environments, Significant changes have been observed where predators have decreased: “Think of the decline in the number of lions, which has led to an increase in the number of baboons. So much so that in some parts of Africa children go to school to avoid the attacks of these animals, which have become too much and therefore out of control.” Damage to plants has led to an increase in the number of rats. Thus, the absence of white sharks has led to an increase in the number of sharks that were preyed upon by sharks. The fall of sharks in the waters of the United States has led to a significant relapse of ray bursts, such as the decline in shrimp populations. “

There is a second important message behind this study: “In the face of a white shark attack on a sea lion, we naturally take the side of the sea lion, but In reality there are no good and bad animals in an ecosystem, instead there is a balance where even top predators play an important role, as other species contain populations. In short, when we observe the animal kingdom we find ourselves smiling for certain behaviors, but we must be careful that those spontaneous feelings do not return to the direction of the animal. This is because the fear of humans towards the top predators has serious consequences that can be found in the progressive damage we are seeing. “

The absence of the prey quickly changes the behavior of the prey

The state of shark conservation in the Mediterranean, and more generally in the world, is “not good”. Rasotto explains: “This image of a dangerous creature that frightens us, on the one hand, provokes a prey to flee from humans and secure shores. On the other hand, some regions of the world are interested in sharks. A gastronomic point of view There are specific fishing targets for each response. “

Focus mainly on the fins: “Over the years, action has been taken, even by the European Community, CounterSpecifically, The practice of finishing

It should be remembered that these species have biological characteristics that make them vulnerable: sharks have very few offspring, reach late sexual maturity and then start breeding a few years after birth. “The population of all top predators has always been limited – as Rasotto points out – many human activities towards sharks have led to their rapid decline.The emotional side: When several species of whales and dolphins found themselves at risk of extinction, there was a global association that eventually led to the suspension of fishing. And why is this successful? Because emotionally the dolphin is an interesting animal and the whale does not scare. In the case of sharks, it is difficult for humans to get involved because, emotionally, one is considered their worst animal: In order to protect them, it is important to focus on the preaching workWhich can help free them from this unjust reputation. Recall what has already been said: “There are no good animals and no bad animals”.

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