Guess what we’re talking a-BOAT on the River Authority blog today…The 2021 MRINS is oh-FISH-ially complete!

Written by:

Posted on:

Categories:

Share:

Facebook
Twitter
LinkedIn
Email

Get The Latest:

Join our print or digital newsletter to be informed about the agency’s many projects and other news.

A yellow bullhead catfish stares mouth agape while being held by a hand.

A yellow bullhead catfish! One of the many species found in the 2021 Mission Reach Intensive Nekton Survey (MRINS).

After six long days trudging through thick riparian vegetation and wading through deep waters, the 2021 Mission Reach Intensive Nekton Survey (MRINS) has concluded. You might be wondering, what the heck is a “nekton”? Although it sounds like the latest trending cryptocurreny, the word nekton is science-speak for an actively-swimming aquatic organism, or more simply, a fish! San Antonio River Authority (River Authority) aquatic biologists and many volunteers from various River Authority departments have conducted this survey for three years (and counting). The MRINS began as an effort to gauge the effectiveness of the ecological restoration within the Mission Reach of the San Antonio River Walk. The restoration, completed in 2013, aimed to find the nexus between flood conveyance and ecological functionality. The first annual MRINS was conducted in 2019, several years after the initial restoration, to allow the new habitats to attract native fish back into the Mission Reach. The goal of the MRINS is to track new fish species that have returned to the Mission Reach and monitor a variety of trends in fish community metrics such as percent native and non-native fish.

The MRINS comprises five sampling areas, beginning with the mile-long Eagleland stretch. The Eagleland stretch is often seen as the transition between the more urbanized downtown River Walk and the more natural stretches downstream of the Mission Reach. The habitats encountered in these areas include everything from swift, shallow water with a turbulent surface that can be sampled on foot, called riffles, to deep pools that require a boat. Now you can see why we call it an intensive survey!

A foot crew carries a special electric backpack worn by one person to temporarily immobilize the fish (This method causes minimal stress to fish, as they recover quickly and are released soon after observations are recorded!). At the same time, two other scientists have nets to catch the immobilized fish.

Two people in knee deep water hold partly submerged net to capture corral fish at the bottom of the river.

 

This foot crew also has a long net with poles on each end that is dragged along the river’s bottom to corral fish.

The boat crew has a similar electrical system used to temporarily immobilize the fish; however, this electrical current is delivered directly from the boat.

During the MRINS, multiple habitats are assessed through each reach because different fish prefer different habitats depending on how they feed. Collection methods vary based on the habitat type being sampled. Therefore, all habitats must be surveyed effectively. For instance, if you sample a riffle, you are more likely to find a central stoneroller or Texas logperch. In contrast, if you sample a backwater, you are more likely to find a western mosquitofish or golden shiner. After each sample, every fish is identified to species and measured. It is also essential to describe the environmental conditions that each fish is coming from. This includes dominant substrate, instream cover like woody debris, overhanging vegetation, and undercut banks as well as water quality measurements such as pH, dissolved oxygen, temperature, depth, and stream velocity. After the conclusion of each sample, all fish are released back into the water and make their way back to the spot they call home in the San Antonio River.

Three River Authority scientists pose in front of floating boat after fish survey has been completed.

The valiant MRINS boat crew: aquatic biologists Angelica Rapacz, Austin Davis, and Zoe Nichols.

Calling all river detectives! There’s something fishy…

Each year brings new fish species, and this year produced our most significant find to date. This mystery fish has an elongated body, is heavily armored with ganoid scales (think diamond-shaped, this fish is fancy!), has an extended jaw filled with sharp teeth, and can gulp for air (say what?!).

Can you guess what it is?

We’ll reveal the mystery fish on our social media accounts next week. Follow us to stay in the loop!


facebook icon circular

instagram icon circular

twitter icon circular

 

Related Articles

Alerts

Stem Density Efforts

Please be advised that trails near the Confluence Park and Conception Park area will be temporarily closed due to ongoing Stem Density efforts. We appreciate your cooperation and ask that you remain mindful of workers and closures when in the vicinity. Thank you for your patience as we work to improve our natural spaces!

 

Gas Spill

The San Antonio River Authority and the City of San Antonio are actively working to contain a recent gas spill in the Downtown River Walk Loop area, which occurred earlier today. The source of the spill is unknown but has stopped. At this time, no environmental impacts have been observed, and teams are implementing measures to fully contain and remove the substance. We will provide updates as the situation develops.

West Bank Trail Closure Notice

Due to the construction of a new trail and bridge, the West Bank of the trail between Schiller St. and Newell St. will be closed for the next couple of months. The East Bank will also be intermittently closed on Monday, November 4th, to install the bridge. Please use caution when navigating around this area. We apologize for any inconvenience.

Please refer to the map for reference. 

San Pedro Creek Culture Park

The restrooms at South Alamo will be temporarily closed for maintenance and repairs. We apologize for any inconvenience and appreciate your understanding. 

Acequia Trail Notice

The Acequia trail will have heavy traffic near MROC starting May 22nd until further notice. The SAWS Acequia project will be bringing in crews to work on the lift station site and across the street. There will have flaggers to stop traffic, please use caution. 

SASPAMCO Paddling Trail

The SASPAMCO paddling trail is open from River Crossing Park to Helton Nature Park.
*Please Note: Paddling Trail from Helton Nature Park to HWY 97 is still closed due to blockages. 

River Reach Newsletter and Blog Signup

River Reach is offered as a printed, physical mailing to your residence or business. The Blog is a weekly electronic email with news and updates in order to be more environmentally conscious. Please fill out the form below and indicate your preferred method of delivery.

By submitting this form, you are consenting to receive marketing materials from: San Antonio River Authority, 100 East Guenther St., San Antonio, TX, 78204, US. You can revoke your consent to receive emails at any time by using the SafeUnsubscribe® link, found at the bottom of every email. Emails are serviced by Constant Contact. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.