Speargunning on scuba, it's just not cricket
I often hear this objection, but I've never read a coherent explanation of the ethics behind it.
Cricket is a sport played by opposing teams who agree to follow rules that define a common objective and give teams probabilities of winning that are approximately proportional to their relative levels of skill, experience, organization, effort, and motivation.
Fishing is an entirely different sort of activity. Fish and people define winning differently. Fish do not recognize any rules. Even when I am equipped with scuba gear, fish are vastly more skilled at swimming and hiding than I ever will be at diving or searching for them. Even when I "win" at spearfishing by my standard of bringing home a suitable harvest, nearly every fish in my vicinity also "wins" by its standard of not getting shot.
There is no reason to attempt make spearfishing a "fair" or "sporting" inter-species encounter. Where I live, fisheries conservation is generally managed by regulating the size of the harvest, not by making the harvest more difficult or dangerous.
When I spearfish, I am not engaging in a sporting event. I am procuring meat for the family table. I shoot legal quantities of legal species of legal size in the authorized seasons.
Why should I feel any obligation to make procuring meat more difficult just to satisfy someone else's vague aesthetic impulses? Why should I unilaterally surrender the means that allow me to take large fish that reside below the depths at which I could free dive? Why should I be shamed into taking the additional safety risks of free diving in order to harvest legal fish?
Please explain your basis for deciding that free diving is acceptable but scuba gear is not. Why does scuba gear tip the scales too much, and why do masks and fins not? By what standard should one decide how many bands of what thickness are sporting for shooting a particular sized fish from a particular distance? Does every innovation in tactics and equipment need to be evaluated to see if it upsets the competitive balance? Ultimately, your standards are arbitrary and idiosyncratic. You're free to honor them, but no one else needs to unless they fish in locales where the laws require it.
Please persuade me that your "just not cricket" comment is anything other than an inapt metaphor in the guise of a rational argument.