The zeta shark actually has little in common with its terran namesake. This was due to the fact that no xenobiologist was part of the original colonial survey team and thus named on a subjective response to its basic form.
Like the sea going mammals and reptiles of Earth, they are air breathing and their flippers are modified legs from their former terrestrial existence. Tho warm blooded as adults, they are cold blooded as juveniles and are hatched from eggs that are laid in the sand of tropical beaches like terran sea turtles by the adult females.
The advantage of exothermic juveniles is that they food needs are much lower than adults and living in tropical climes there is little need for internal thermal regulation. The adults normally live in temperate or subtropical waters in winter but migrate to polar regions in summer to feast on the rich invertebrate life of shallow estuaries. Thus, the juveniles and adults never compete for food resources.
In the late fall of the respective hemisphere, the adults migrate to the zone just poleward of the ITCZ, Inter Tropical Convergence Zone, and lay their eggs on small island beaches. The ITCZ moves further into the opposing hemisphere leaving these beaches dry and warm during the winter. On completion of laying eggs the females return to the sea where the males are waiting, in less the one meter deep water, to complete for mating with them. It is during this time, if the creatures come into contact with humans, that has made them of interest to the Xeno Labs.
Actually the contact was inevitable, the native world is very amenable to humans and has attracted large numbers of Pacific and Caribbean Islanders. They have found the huge number of tropical islands good places to pursue traditional lifestyles in the post-capitalist economy of the galactic Imperium. In addition, the waters of this world have few truly dangerous inhabitants.
The zeta shark is extremely intelligent, on par with humans and cetaceans. This was not readily apparent to humans, due to the bias for large brains and not complex decentralize nervous systems as signs of intelligence.
They also possess sonar like cetaceans and can use this as ultrasound to see the internal structure of others. Reproductively, humans and zeta sharks aren't all that different internally. When the creative, intelligent mind of a newly matured male zeta shark meets the frustration of being out competed by larger mature males and the apparent compatibility of human females, who have become available, mix, certain problematic issues have emerged.
Unfortunately, sentient beings that are largely aquatic are far more alien to us than terrestrial ones. The communication between our species and theirs is very limited. But from what we can gather, they:
1. Legitimately see it as their world but don't mind sharing it if we play nice.
2. Like most aquatic sentients, they aren't big on the human obsession with morality.
3. Thus, see the issue as "meaningless" and don't see why humans should complain.
4. And, therefore, see no reason to prevent the frequent attempts at mating with human females by randy young males that, in fact, help with some of their own problems caused by this situation.
The colonists have complained but seeing that killing the zeta shark is murder, under colonial law, and the law is ruthlessly enforced, since, there are powerful alien species willing to go to war with us if they are not, they can do little to stop it. Thus, the situation has remained unresolved.
We at the Xeno Labs have taken great interest in this situation. Our subsidiary lab on the zeta shark's homeworld has conducted extensive research in the field to better understand the copulatory behaviors of these beings, and to promote a better appreciation of the very tender manner of mating with willing women.
We have found that they prefer prolonged oral stimulation of their mate with their sucker mouths and will copulate with them for several hours when given a chance. In addition, even older males will stop to mate with human females during the height of mating season once they having mated with one previously. Also, males will mate with humans outside of mating season once initiated into this type of contact so matings with humans occur in all regions where the waters are warm enough for prolonged contact.
Thru, literature about, and videos of matings, of human females by zeta shark males we have greatly increased the understanding of the colonists and their tolerance for these events. In fact, despite some denial by colonial authorities, such matings have become more frequent and even acceptable as public awareness increases thru the work of the Xeno Labs. We are only pleased to be involved in helping others come to terms with the situation.