Is It Wrong for Divers To Take Marine Life?

[rubber chicken]

DOG-EAT-DOG
Quite literally! Big fish eat little fish! Often in a more 'savage' method.
I don't know if you've seen video's of seals, turtles, or other sea life being ripped apart by bigger fish.

I'm aware that nature is 'red in tooth and claw'. What I am questioning is the implication that without humanity 'carefully harvesting' these animals their survival is in doubt.

Most prey/predator relationships exist as a feedback loop. Too much predation and the prey population crashes and the predators starve. Humanity is not part of that loop, except on a global scale.
To argue that underwater hunting is necessary in order to 'manage' populations of 'resources' is utter nonsense.
You can claim the right to take marine life on the grounds of necessity or economics or even pleasure but, please, don't try to claim that you are doing the animals a favour!

[hbh2oguard]

Humanity is not part of that loop, except on a global scale.

Humans are part of the loop, they're at the top as the apex predator in most cases. I couldn't agree more that harvesting the animal isn't directly helping that animal but it might be helping another animal, altering the marine ecosystem indirectly.

[rubber chicken]

AFAIk there is NO marine ecosystem which evolved with Humans as part of it. Our interference is only possible through the use of technology, most of which developed, on an evolutionary timescale, an eyeblink ago.
If we knew enough about the incredibly complex interactions involved in any marine ecosystem to be able to predict, with any degree of accuracy, the possible results of our actions, then we could say that, on the balance of probability, our activities would be benign or even beneficial. However, we don't and we can't.