Isabelle Farrell's Blog: Gila Topminnow
Gila Topminnow (Poeciliopsis o. occidentalis)
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Description and Ecology
Gila topminnows are a small guppy-like fish that can be found in small streams or large rivers in both Arizona and New Mexico. Gilas like tranquil, shallow, warm water, but can really live just about anywhere because they are fast at adapting. A great example of this is one reestablished population that survived for sixteen years in a cement watering trough. You would think their resilience would aid in their ability to survive, but unfortunately other factors have led to their endangerment.
Geography and Population Changes
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Gilas get their common name from the Gila River in Arizona where these little fish were once most commonly found in the 40's.But habitat destruction and degradation as well as the introduction of the nonnative Western Mosquitofish cause Gila numbers to plummet.
Listing Date and Type
The topminnow was listed as endangered in 1967. A formal Recovery Plan for the little fish and two subspecies was finalized in December of 1998.
Cause of Listing and Main Threats
Although reintroduction has been attempted multiple times, the Gila's numbers continue to decline and has remained on the Endangered Species list. The introduction of the Mosquitofish has had a huge impact on Gila populations. Mosquitofish look very similar to Topminnows. They are both small and tan, but Mosquitofish have black spots on their dorsal fin. Because the Mosquitofish is so similar to the Topminnow, they compete for food and habitat. Mosquitofish have been successful in driving out Topminnows because Mosquitofish fecundity is incredibly high. Female Mosquitofish can produce up to 315 embryos each brooding period, which occurs 3-4 times per year. Mosquitofish also prey on young Topminnows, and spread infections. Other introduced predatory fish, such as the Largemouth and Smallmouth Bass cause declines in Topminnow populations, but nothing like the destrution caused by Mosquitofish.
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Mosquitofish
Gila Topminnow
Habitat destruction and degradation also heavily impacted the Gila Topminnow populations in the Gila River Basin. Increased overgrazing and logging in the area surrounding the Gila River, in combination with drought in the early 1900's, caused erosion and severe flooding when droughts ended. This altered the river flow, and destroyed much of the Topminnow's habitat.
Description of Recovery Plan
The Gila Topminnow's Recovery Plan is broken down into six tasks to ensure their recovery.
Task 1: Prevent Extinction by Protecting Remaining Natural and Long-Lived Reestablished Populations
Only 8 naturally occurring metapopulations remain in the US, and 13 reestablished populations.In order for Gila numbers to rise, captive populations in schools or aquariums are encouraged. In addition, critical natural habitat is being protected for the Topminnow. Also, the introduction of non-native species is prohibited in areas where Gila populations naturally occur. Scientists are still conducting research to come up with a viable minimum population for Topminnows because that has yet to be done.
Task 2: Reestablish and Protect Populations Throughout Historic Range
As well as introducing more Gila into the Gila River, new habitats will be scouted in order for Topminnow to be introduced as well. New sites with an elevation less that 1,600 m is optimal for these little guys.An example of a suitable site is Aravaipa Creek in Southwestern Arizona.
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Task 3: Monitor Natural and Reestablished Populations and Their Habitats
Once a year Topminnow populations need to be checked to ensure their health is maintained and hopefully their population is growing.m
Task 4: Develop and Implement Genetic Protocol for Managing Populations
Genetic exchange needs to be facilitated in reestablished populations so that gene pools can be kept diverse. Scientists do not want Topminnow populations to bottleneck and reduce genetic flow.
Task 5: Study Life History, Genetics, Ecology and Habitat of the Gila Topminnow and Interactions with Nonnative Aquatic Species
Many things about the Gila are unknown, and scientists believe that the more they know then the better they will be able to help the Topminnow recover.
Task 6: Inform and Educate the Public and Resource Managers
If the public is educated about the importance of the Topminnow, and understands that they can help protect the small but vital fish, then the Gila will have a better chance of survival.
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These wonderful biologists are releasing Gila Topminnows on May 15, 2017. This project has been going on for more than 25 years.
What Can You Do?
The best thing someone can do who is not part of the US Fish and Wildlife or Forestry Service, is to be aware that Topminnows are an important part of our Earth's ecosystem. Don't underestimate their small size because they eat mosquitoes that carry viruses that can be spread to humans, and algae that could take over small ponds and streams. Simply being aware will help these little fish recover faster.
Other Sources/Work Cited
Phoenix Zoo
http://www.phoenixzoo.org/conservation/local-conservation/gila-topminnow/
Info on Aquatic Life Conservation in Arizona
https://inthecurrent.org/fs/1207/
Gila Topminnow Recovery Plan
https://ecos.fws.gov/docs/recovery_plan/990305.pdf
Great job on the blog! Upon reading this, I was wondering how exactly the mosquitofish were introduced topminnow's habitat. Was it unintentional or intentional? I know that you mentioned that it was one of the main threats to the species was the introduction of the mosquitofish, but am curious to understand the underlying cause.
ReplyDeleteAwesome job, I had no idea that the topminnow was capable of eating mosquitos!
-Jay Gubbi
Amazing that these little guppy fish are so fast to adapt. On my ranch at home, we always put gold fish in our water troughs to help keep the water clean. It's crazy that they could live up to 16 years!
ReplyDeleteGreat article!
~Brody Gill
That story about the population of topminnow surviving in the cement watering trough for 16 years was very interesting. A shame that their adaptability isn't enough to overcome competition from the mosquitofish.
ReplyDeleteGood job!
-Cole Fukai
The poor Gilas being driven out by bigger fish like the Mosquitofish and Large-mouth Bass is sad to read about. I like how you broke down the tasks needed to be performed to help increase the Gila populations. And they eat mosquitoes so I'm all for them! Great job on this blog!
ReplyDelete-Josh Gillespie
It's unfortunate that there have been many attempts to reintroduce this tiny fish. It's always interesting when a tiny species like this can have a larger effect on the world even though that effect isn't thought about, but since they eat mosquitoes they even help people's health. Let's hope their population can grow to a stable size.
ReplyDelete-Samantha Friesen
Wow, it is crazy how this small fish is still being effected by habitat destruction over 100 years later! It really looks as though they have an expansive plan to recover the population of this species. That is so exciting to here. It is also so nice to hear that they are helping humans with the huge problem of infectious diseases spread by mosquitoes.
ReplyDelete-Katie Halstead
I haven't heard of Gilas before, and it was interesting to learn a little bit about them. It's crazy that there are so many endangered animals out there that people haven't even heard of before, and yet we as humans are putting them in danger. I found it interesting that another small fish, the mosquitofish, could have such a big impact on the Gilas. Great job on your blog!
ReplyDelete-Rebekah Fesmire
Its wild that the gilas could survive in a cement trough. People often do not take the small animals into account because they seem abundant, but in reality there aren't many. With another small fish in the same environment praying on the gilas I feel like it can be hard to protect them. The blog is great, good job.
ReplyDeleteGavin Griffin