For the second time the annual meeting of the Western Society of Naturalists (WSN) was held in Mexico, acknowl edging the importance of maintaining and augmenting col laboration and communication across regions within the California Current ecosystems regardless of political bor ders. To commemorate the society’s “centenario” or 100th meeting and to mark the commitment among members to maintain international collaborations, this Ciencias Marinas issue includes 10 manuscripts from research presented at the WSN meeting held in Ensenada, Mexico, from October 31 to November 3, 2019, where 235 talks and 121 posters were presented. In concordance with the special topics addressed throughout the conference, here we present a brief summary of the history of marine research in northwest Mexico and emphasize how these efforts have changed through time. We also discuss the importance of continuing international col laborations to improve our understanding and management of ecosystems within the Northeast Pacific, as well as the role WSN plays in fostering transboundary international research.

Although indigenous communities of the region have held vast knowledge of marine species, coastal currents, and coastal geography, historically academia has failed to include and preserve indigenous knowledge. As such, the most com monly accessible early data from the Northeast Pacific on these marine subjects comes from Spanish conquistadores in the 1700s (^{Del Barco 1988}) and American whalers in the early 1800s (^{Scammon 1874}), who traveled extensively along the coast and published their observations. These early publications in the late nineteenth and early twentieth centu ries were mainly descriptive, focusing on taxonomy (^{Verrill 1869}) and species distribution (^{Jordan and Evermann 1896}). In particular, these early observations highlighted the differ ences in fauna between the Gulf of California and the western Pacific coast side of the peninsula, and the similarities in fauna between Baja California and California (^{Deichmann 1941}).

Despite the two World Wars resulting in a general hiatus in research, some “amateur” naturalists generated some quintessential information during this time and shortly after there was a swell in academic research (^{McClatchie 2014}). For example, the book “Sea of Cortez: A Leisurely Journal of Travel and Research” by ^{Steinbeck and Ricketts (1941)} still represents the best available “pristine” baseline to compare to current conditions along the region (^{Sagarin et al. 2008}). Sci entific research programs such as the Allan Hancock Foun dation Pacific Expeditions and the California Cooperative Oceanic Fisheries Investigations were created and improved the knowledge exponentially of the marine fauna and flora of California, northwest Mexico, and the entire Eastern Tropical Pacific (^{Clark 1938}, ^{McClatchie 2014}). Moreover, there was a surge in research during the 1950s and 1960s, and several US institutions, such as Scripps Institution of Oceanography, the American Museum of Natural History, Stanford Univer sity, the University of Southern California, San Diego Nat ural History Museum, and the University of California in Los Angeles, conducted research in northwest Mexico on varied subjects such as oceanography, ichthyology, and paleontology (^{Durham and Barnard 1952}, ^{Hubbs 1960}, ^{Roden 1958}).

During this same period in Mexico, only a handful of uni versities offered undergraduate programs in biology, such as Universidad Nacional Autónoma de México (UNAM), Instituto Politécnico Nacional, and Universidad Autónoma de Nuevo León, and so the first (taxonomic) papers written by Mexican researchers on the marine fauna of the Pacific appeared (^{Rioja 1948}, ^{Caso 1953}). Systematic research on marine species of northwest Mexico started in the 1960s, likely fostered by the interest of the federal government to increase commercial fishing (^{Castro-Aguirre 1965}). In 1960, the Universidad Autónoma de Baja California (UABC) estab lished the Escuela Nacional de Ciencias Marinas, with a Bachelor of Science degree in Oceanology, the first in Mexico and Latin America, and initiated oceanographic research in Mexico. Subsequently, most university marine science pro grams throughout the country (i.e., marine biology, fish eries biology, hydrobiology, oceanology) started in the 1970s (^{Martin del Campo 1987}).

The Consejo Nacional de Ciencia y Tecnología (CONACYT, Mexico) was founded in 1970 with the goal of strengthening the development of science and technology in Mexico. The CONACYT budget reached an all-time high in the 1980s, and the number of marine research proj ects increased dramatically, particularly in the northwest. In 1981 Mexico bought its first fully-equipped oceanographic ships (“El Puma” and “Justo Sierra”, owned by UNAM and Petróleos Mexicanos; ^{Hendrickx 2012}). During this period, CONACYT’s national and international graduate scholarship programs were established. Throughout the 1980s research conducted by Mexican scholars increased, but most pub lished research was done by US scholars (Fig. 1), in part due to the lack of PhD programs in Mexico. However, through CONACYT’s scholarship program, many students were able to obtain master’s and doctoral degrees abroad (e.g., ecology, aquaculture, and fisheries), mainly in the USA, Japan, the UK, and Spain, leading to subsequent increases in Mexican research publications.

Figure 1 Percentage of marine science articles published from research done in Northwest Mexico by decade and country of the institution of the first author. The data were obtained by searching the Web of Science database using the key words “Gulf of California OR Pacific Coast Baja California”. Total number of papers found per decade are in parenthesis. 

In the 1990s, many Mexican students who had studied marine sciences abroad began to return to Mexico and con tinue their research. By then, Mexican marine research insti tutions were also awarding master’s and doctoral degrees, and funding was available for research from government sources, such as CONACYT, which increased the quality of research and the output. Coordination, collaboration, and exchanges with US researchers continued, but increasingly Mexican scholars worked independently. By the 2000s, the undergraduate students of the 1970s and 1980s were now independent researchers with over 10 years of experience. Globalization also played a role in diversifying and strength ening marine science in Mexico; many PhD graduates from Europe (mainly Spain) and South America arrived to Mex ican institutions, providing further avenues for diverse col laborations. Additionally, non-governmental organizations, such as ProNatura Noroeste, Sociedad de Historia Natural Niparajá, Comunidad y Biodiversidad, and many others became key actors supporting marine research in northwest Mexico with grants from national and international founda tions and governments.

Finally, in recent years, Mexican scholars accelerated their output to the point that the majority of marine research pub lished in the last decade (2010-2019) in Northwest Mexico has been authored by Mexican nationals (Fig. 1), although researchers from US institutions still produced around 40%. These trends and evident historically shared research interest among USA and Mexican scholars present great opportuni ties for continuing to foster and strengthen transboundary academic collaborations, a common theme during the 100th WSN meeting.

The synergistic nature of collaborating among scientists from different countries is an ideal to continue to strive for. Within this WSN special issue, the 10 articles published are a very small fraction of all the collaborative work presented and cited during the meeting but still highlight how research is enhanced by such diverse collaborations. The research by Bauer et al. (this issue) integrated wide perspectives from Mexican and USA researchers and a local fishing cooperative to inform aquaculture, management, and conservation of a valuable, endangered fishery. Other binational collaborations include Tholan et al. (this issue), who described the ichthyo fauna of remote and rarely studied islands in Pacific waters off Mexico, and Velasco-Lozano et al. (this issue), who ana lyzed mesophotic fish communities in the southern Gulf of California and identified the reservoir of species found at these previously unknown depths that are in need of protection.

Other papers within this issue are also of key regional relevance. Lowe and Galloway (this issue) identified a greater depth range of red sea urchins than had previously been reported, information relevant to the management and future research of this important marine resource that distrib utes from Mexico to Canada. Vendetti (this issue) described the larval development of the Kellet’s whelk, a large gas tropod that is part of an emerging fishery in California and Baja California. Leonardi et al. (this issue) analyzed the mor phological variation of colloblasts (specialized cells for pre dation) from 20 species of ctenophores, contributing to a better understanding of the functional diversity of pelagic spe cies. Vargas-Peralta et al. (this issue) reported the complete genome of the halibut, Paralichthys californicus, improving the knowledge of a species that is distributed and exploited across the temperate northeastern Pacific. Hansen et al. (this issue) highlighted the strong negative impact of introduced red mangroves on endemic Hawaiian fish populations, sup porting the need for eradication of the invasive mangroves. Payan-Alcacio et al. (this issue) described the functional fish diversity in arid mangrove habitats of the Gulf of California, highlighting this important yet fragile ecosystem. Dolinar et al. (this issue) quantified the effects of mooring distur bance on rhodolith community ecophysiology, a research with broad implication to management of this important eco system both in Mexico and the Northeast Pacific (highlighted ^{Cabello-Pasini and Riosmena-Rodriguez 2007}).

Transcending political borders and promoting collabora tive work among nations is an important goal in the manage ment and conservation of shared marine resources. Canada, the USA, and Mexico share marine resources and a long his tory of social, economic, cultural, and ecological interactions. In our dynamic and stochastic world, and particularly in a region as the Northeast Pacific, transboundary research is not only an important goal but also meets a definite research and management need. A transboundary, interdisciplinary, and collaborative approach to research projects fosters greater breadth and efficacy when tackling complicated issues that do not stop at political borders. The WSN intends to con tinue to support such essential communication and collabo ration among a diverse array of scientists regardless of race, gender, religion, sexual orientation, disability, socioeconomic background, language, ability, age, and political perspective in order to shed light on the common ground of elucidating ecology, evolution, natural history, and marine biology.

We gratefully acknowledge the wide range of support received that led to both the 2019 WSN Ensenada meeting and this special issue of Ciencias Marinas. We are indebted to the support from the WSN, UABC students, faculty and administrators, Hotel Coral y Marina, invited speakers, and meeting attendees. This special issue of Ciencias Marinas was improved by the work of special issue section editors, reviewers, and authors. We would like to specially thank Lucía M Rodríguez and Sarah J Teck for their valuable comments. All of these contributions to the meeting and journal are an example of collaborative investigation and work.