Ok, I'm hearing rumors that the annual RP fishing tournament is stirring a lot of controversy from the "All you fisherman A-holes are raping the ocean" crowd, so I was pulling together my library of articles and scientific research about our fishing area, and thought this would be a good time and place to share what I've learned.
I thought it might be valuable to others here in the fishing forum that want to learn more about the ecology, species, and biologies of the reefs we fish (and dive) on in the upper Sea of Cortez, and might help those of you that are pre-disposed to express disdain toward sport-fishermen for the "rape and pillage" image that we project.
I am a responsible sportsman - I study the nature of the sport I enjoy. I have no interest in catching the "last" grouper in the Sea of Cortez. When I take fish to consume them , there is absolutely no waste, and I make sure every shred of edible flesh is consumed. I even donate the heads to the guys at the Marina (or other locals) to make soup from (a 30 pound gulf grouper can produce about 2 pounds of edible flesh from his head alone).
Below I will post several scientific articles and resources to back up my points, but here are the "cliff's notes" and some of the most common misconceptions I've come across in the years I've been fishing these waters and talking with other people about grouper fishing:
1) Wrasses and Groupers are
not all males that later turn to female - it is the opposite. All wrasses (sheepshead is the most common one we catch) and
ALL Grouper species are born female. Only the most aggressive and territorial will "convert" to males. They are "harem" spawners- the males are solitary until spawning time, when they herd up a group of females and spawn with them repeatedly until the spawning season is over.
2) Prior to popular belief (and opinion) - Grouper do NOT have small reproductive rates - a single 10 pound Sardinero can produce 5 milllion eggs in one season, and will spawn an average of four times between mid March and early June. Ditto gulf Grouper, who can produce up to 20 million eggs in one season.
3) Grouper do not "nest" when they spawn. They aggregate (school up) in large numbers, and the males "round up" and spawn with their own individual harems of females. The fertilized eggs drift in the current, and hatch after about 30 days. The hatched larvae spend the rest of that season drifting in the plankton. When the larvae finally drop out of the planktonic phase, they begin eating (and growing) aggressively.
4) Grouper are NOT slow growing - and they do not live for centuries. A Gulf Grouper will be about 5 pounds (and fishable) 2 years after they drop out of the larval (planktonic) stage. The average 20-40 pound Gulf Grouper is about 5 years old. a 5 year old Sardinero can be 10-25 pounds. The biggest 200 pound+ Gulfies might be 30 years old. Biologists "age" groupers using bones in the ear that form seasonal rings (like a tree).
There is no scientifically substantiated evidence of Gulf Grouper living more than 50 years- the longest lived Gulf Grouper on record was about 35 years old- the same as a large (30 lb +) White seabass, or the same as a large (40lb+) yellowtail. Funny how no one ever goes all crazy about someone catching and keeping a 30 year old White Seabass...?
Black seabass are indeed very long lived (75 years or more), and are highly susceptible due to lower reproductive rates, but Black Seabass also move around alot more than grouper do - the two only share similar external appearance, they have totally different biologies, physiologies and behaviors.
5) The harvest of Grouper by sportfishermen (assumming they adhere to their legal limits) is statistically insignificant to the population density of these species. The by-catch of commercial shrimping (as well as deliberate over-harvest by commercial panga operators) is the largest population threat to these fisheries- and if you completely eliminated sportfishing alltogether, the result would not be an increase in any species' survival or population rates.
6) Regarding Gulf grouper being listed as endangered - This data is skewed by the Gulf grouper's naturally limited home range - this is not a globally common species- but within its natural range, Gulfies are not "uncommon" at all; nor is the number of REALLY big (150lb+) fish - Every time we are out fishing for grouper, our "lost to landed" ratio says that there a bunch of fish out there that are simply too big for sport fishermen to deal with using rod and reel. when a fish can pull drag (and ultimately break) 200lb test fishing line, then that fish ain't no 80 pounder.
The technical limits of the average rod and reel naturally limits the harvest of monster grouper - they simply overwhelm our gear far more often than we get them out of the rocks and up to the boat. So, just because the pictures we all post from our trips seem to "top out" around 80-90 pounds does not mean there are no bigger fish out there. They are out there.
7) Back to the whole "male versus female" thing - I think a lot of people confuse grouper population dynamics with freshwater bass (where the males are smaller and outnumber the larger females 5:1), and where removing females (especially at spawning time) is damaging - THIS IS 100% INACCURATE with regards to Grouper.
A grouper has to be a mature female who has spawned at least once before she can "switch" to male (the ovaries actually convert to testicles due to hormone changes) - Here are more facts:
- Once male, a grouper can never "go back" to female.
- due to age, size, and population distribution statistics, just about EVERY 100lb plus Gulf grouper will be male. Removing these fish reduces the already disproportionate male to female ratio. (That's why no one has seen a picture taken on my boat of a 100lb+ fish - I will simply NOT allow one that big to be brought aboard and kept- but that really doesn't matter- Like I said above, most 100lb and bigger fish release themselves shortly after being hooked anyway, and all the fisherman gets is that "snap" feeling and the opportunity to break another $4 hook out of the tackle box.
So, when you catch a 50-80 pounder that is full of eggs, that's not a bad thing- it's a good thing, because fish in that size range are SUPPOSED to be females. Taking a big one WITHOUT eggs would be bad, becasue you are removing the already more rare males; and it can take 2 years for a female to complete the "sex-change" and become a spawning-capable male.
So, Here are all the scientific studies that will back up the points I expressed above. I encourage everyone to read, study, and discuss these data, but don't think for a minute that you are going to show me the "error of my ways"... I enjoy fishing. I do it responsibly, and if you try to get in my face with your "enviro-religion" then I am going to debate you with FACTS.... so you better be prepared.
Gulf Grouper- biology, and sexual lifecycle:
http://www.reefresilience.org/Toolki...0_Problem.html
http://www.iucnredlist.org/apps/redlist/details/14049/0
Leopard Grouper (aka Sardinero) age and growth rates:
http://scholarspace.manoa.hawaii.edu/bitstream/handle/10125/2497/v55n2-171-182.pdf?sequence=1
Summary- most of the Sardineros we catch between 10 and 25 pounds are about 5-10 years old.
Sea of Cortez Ecology, populations and harvest rates for a bunch of different Serranids, including the Groupers and Gold Spots:
http://cmbc.ucsd.edu/People/Students/aburto/Ciencia_y_Conservacion_Vol2008No1_eng.pdf
Now, the one species that I have not found a ton of research on are Pinto Bass, but I did find some interesting videos about Nassau Grouper spawning rituals and fishing policies in the Carribean. The Nassau Grouper is in the same scientific Genus (Epinephelus) as Pinto Bass, so I would bet that Pintos spawn in a similar "mass spawning" fashion:
http://www.youtube.com/watch?v=JFbJsj8KdSI
Like I said- This post is intended to help educate and spread factual scientific data. If it inspires discussion, then that's great, but if it leads to ad hominem attacks against sport fishing, then the gloves are coming off...
