Native Ranges provided starting in Version 2

(keep scrolling down to see how we edited them in Version 3)

Above is an example of one species' native range  (Notropis bairdi) copied Macrhybopsis tetranema) native range copied from the website's map tab.  Native Native ranges for all freshwater species and most marine species in our study area can be found on the project's map tab as a map layer. Open the map, select a species, and select the native range layer. Dark grey HUCs are native areas, light grey HUCs are possibly native, and white HUCs are non-native.

We relied on criteria for determining nativity described by Hoagstrom et al. (2009) and Webb (1985). Native distributions were defined as the full natural extent of each species within Texas prior to human influence (prior to anthropogenic influence over the last 500 years (i.e., European immigration)). Information we had available and frequently accessed during the decision-making process included: NHDPlus Ver 2 hydrology layers, various websites such as NatureServe, Fishbase, and publications listed below. Although we had these resources on hand, we were aware of the fact that knew their data, in some cases was suspect and often not substantiated by vouchered specimens and, we presumed, in some cases, that those authors were determining distributions based on one another's data and so there was subject to circularity. To avoid the possibility of perpetuating possible mistakes, we relied most heavily on Fishes of Texas data, especially older specimen records that had been examined by our team. However, when that was lacking, we relied strongly on those authors (especially Hubbs) who were alive closer to the time-frame timeframe when native distributions were more intact, and we assumed they may have had insights that we lacked.

• We established consensus opinions of the native distributions of all Texas freshwater fishes, defined at the scale of USGS 8-digit Hydrological Units (HUCs).
• While viewing the occurrences held in the project database, one species at a time, we categorized each HUC8 as either (1) “native”, when we could confidently determine so (= strong consensus), OR (2) "possible/probable", when we lacked consensus or all agreed that there was uncertainty in determining a the historical range, OR (3) “non native”, when we could say so confidently determine.
• For many species a buffer of "possible/probable” range adjoins the "native" range.
• The process was largely ad hoc and dependent upon what we knew of the biology of the species and personal experiences or knowledge, but we but we consulted various resources as well (see below).
• Often, we defined native areas as all HUCs with credible occurrences, especially if the specimens were examined by us and were collected prior to 1960s, AND any HUCs connected hydrologically between those HUCs. We typically then, within a basin, defined a set of possibly native HUCs adjacent to the more confidently determined native range.
• In almost all cases the database lacked collections from much of the Llano Estacado (HUCs 12050001, 12050002, 12050005, 12080001, 12080003, 12080004, and 12080006), and two endorheic HUCs (13050003-Tularosa Valley, 13050004-Salt Basin) in the upper Rio Grande - we almost always defined those HUCs non-native for every species. The sand plain HUCs (12110207, 12110208) between Corpus Christi and the Rio Grande were almost always determined to be non-native for freshwater species as well, but sometimes we felt it appropriate to define it as (occasionally “possible/probable”).
• We made no assumptions about which occurrences were based on vagrants or larvae and include vagrants and parts of the range with perhaps only vagrants or larval occurrences as part parts of the native ranges.
• Users will need to interpret the ranges with the understanding that, because we were working at the HUC 8 resolution, there appears to be some extension of the native range beyond what most users would agree as a native range. This is especially true for local endemics, which may occur in a single spring, or marine species occurring in the marine portion of a HUC that extends inland.
• Ranges are In Version 2 of the website, ranges were only determined for all HUC's that at least partially occurring in entered Texas and do ranges did not extend any further into neighbor states or Mexico (future versions will. Starting in Version 3 we extended our native ranges into a larger study area (see below).

Details:

In May and June of 2017, we held a series of nine meetings held mostly as conference calls. Determinations were made via consensus with always three or more people present including the following participants: Gary Garrett (9 of 9 meetings), Ryan Smith (9 of 9), Adam Cohen (8 of 9), Doug Martin (6 of 9), Roy Kleinsasser (1 of 9), Dean Hendrickson (1 of 9), Melissa Casarez (1 of 9).  Ryan Ryan Smith controlled ESRI ArcMap to display all of FoTX’s georeferenced occurrence data alongside a draft of native HUC8 determinations that originated from the Hubbs et al. checklist (2008) , but was edited by Gary Garrett prior to the first meeting. In the course of the meetings, that draft was heavily edited to reflect the FoTX occurrence data overlayed on it.

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See this report for more details.

In 2022 we held additional meetings to expand our native ranges into an enlarged study area and revise them to reflect the large number of new records in the database from the addition of the Track 3 data and revisions to the Track 1 and 2 data (mostly taxonomic re-determinations and updated georeferences). The updated native ranges were introduced with our Version 3 of the website along with the Track 3 data.  Efforts to more precisely georeference our oldest records, collected in the mid-1800’s, greatly improved the accuracy of our native ranges.

Methods were generally the same as our 2017 effort, but we used QGIS software rather than ArcGIS (ESRI). All freshwater species in our study area were assessed in 12 meetings held on June 30 through July 26 by combinations of the between 2 and 8 (mode=6) people experienced in fishes of our region including,: Adam Cohen (12), Doug Martin (10), Roy Kleinsasser (9), Gary Garrett (8), Chris Taylor (8), Megan Bean (4), Kevin Conway (3), Bob Edwards (3), Melissa Casarez (3), Dean Hendrickson (1), and Chris Hoagstrom (consulted for single species). During these meetings we re-determined or determined native ranges, flagged records for examination, as suspect, as captive and/or for re-georeferencing (and other less common data errors).

Some of the resources we reviewed: 

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