Conservation

This isnt about like past posts and stuff, more of a general thing about conservation. For ALL users of this site, I just want you to know that there are reasons for these size limits and bag limits and stuff

Some limits I think need more intensive study yes, like the size limit of 47 inches for swordfish does not make sense because that is a 50lb fish and they are not capable of reproducing until they have reached 150 lbs.

A lot of work goes into learning techniques to access fish populations, it requires a lot of statistics and many years of study. Think about of 4 years of college and then up to 7 years of graduate school to get a PHD. Without that PHD, your pretty much nothing as a marine scientest other then doing field work or helping manage a lab. Really the only way that you can even apply for research money or work for the government in a managment position is with your PHD.

To give you an idea of how scientest figure out size limits ima explain something below. Its called an age and growth curve. Basically what the makeshift one I drew below does is compare the total length of the fish and its age. I made up a lot of numbers here to show you the general Idea and I changed the graph a bit to be more clear to read. So the one i made up below is for "mangrove snapper". Each blue dot represents an individual fish that was collected measured (total length value), then its otolith (an ear bone which when cut open has a ring for each winter the fish has lived) is removed and counted to find the fishes age. The values are then put on this x-y plot and land where they are. So you see obviously that as the fish gets older they tend to get longer but there growth rate varies thats why you have some "3" year old fish at 10 inches and some "7" year old fish at the same length. Remember that the blue dots where the natural growth curb, now look at the red dots. Those are the "actual values" i put it in quotes because I made up this plot to show you guys and each dot isnt actually from a real fish. So you see that the red dots sorta level off at ten inches with some a bit higher but not so many. In reallity the ten year old fish should probably have made it to 17 inches but those fish who grew bigger then ten inches where harvested so the many ten year old fish that should be 17 inches are dead.. and the few ten year old fish we see only made it to ten years old because they grew slower and didnt reach the size limit until way later then many other fish.

The red is how many growth curves look for highly fished species like snappers and groupers. Many fish don't get anywhere close to the size that they could attain simply because they are harvested when they are exactly at the size limit. I'm not saying dont fish for em.. just follow the size limit because there are reasons behind them. I'm not sure but I'm guessing the ten inch size limit for mangrove snapper has something to do with it having passed sexual maturatiy at a smaller size.

You ever wonder how marine scientests set up the sizes for marine protected habitats? A lot of this is done by setting up hydraphones (listening devices) and putting acoustic tags in fish. Each time the fish passes the hydraphone it lets out a ping letting the hydraphone know that that specific fish has past it. This is a way to figure out the moving patterns of reef fish who stay within a small area so that they can protect those certain fish, by knowing how big to make the reserve. Whats the point of setting up a reserve when the fish only spends part of its day there right?

below are some ppl from noaa putting an acoustic tag in a gag grouper off of georgia.

http://noaaacousticfishtagging.blogspot.com/

Below is a diver holding a hydraphone which is used to pick up the signal of acoustically tagged fish in the area.

In alaska fish are actually imaged with hydraphones. Using very high frequency sound (sound that has a very short amount of time between each sound wave) they can get very high resolution of the fish.
In the picture below the top sound wave is a low frequency wave where as the bottom one is a high frequency wave.

Think of your depth sounder. The higher the frequency the more resolution your get because the sound is going to hit the fish twice mabye or three times mabye instead of just once between the sound waves of a low frequency. The problem with high frequency is it doesnt travel as far. Well anyways, back to the point, in a small area, lets say the mouth of a stream or river by setting up hydraphones sending very high frequencies scientest can actually image and count and identify the type of salmon going in or out of the streams and rivers to lay their eggs.

I'll try to find some pics of the salmon stuff.. its pretty cool.. and the alaskan salmon fishery is one of the best managed fisheries in the world.

Facts about slot sizes:

One 10lb snook can have over 10 times the amount of babies that a 5lb snook can.

Some stuff about the oil spill.

We might not see the effects of the oil spill for several years because many of the fish that were effected by the spill have not been recruited into the fishery yet. Recruitment to fisheries scientests is a term that means the fish has reached a size that it will be caught in its fishery. Fish like bluefin tuna who spawn in the gulf of mexico, they probably lost an entire year class. Which means three years from now when we would normally have seen these fish start being caugh (recruited) we will most likely not see those fish whatsoever.

I've gotta get back to my chemistry book... but i hope you guys enjoyed this post and learned something from it. If you wana know anything more about marine science.. id be happy to do another post for you guys from my limited knowledge of the subject.